Revision History for A155032
(Underlined text is an addition;
strikethrough text is a deletion.)
Showing all changes.
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#9 by Susanna Cuyler at Tue Feb 16 01:02:36 EST 2021
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#8 by Michel Marcus at Tue Feb 16 00:45:57 EST 2021
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#7 by Michel Marcus at Tue Feb 16 00:45:53 EST 2021
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| CROSSREFS
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pi(a(n)) = A154963.(n).
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| STATUS
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proposed
editing
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#6 by Jon E. Schoenfield at Tue Feb 16 00:43:54 EST 2021
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#5 by Jon E. Schoenfield at Tue Feb 16 00:19:18 EST 2021
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| NAME
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Primes np such that the concatenation of pi(np) and np is prime, withwhere pi beingis the prime counting function.
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| EXAMPLE
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Since 3 is the second prime number and the concatenation of 2 and 3 gives 23, which is prime, 3 is in the sequence. Since 59 is the seventeenth prime and the concatenation of 17 and 59 gives 1759, another prime, 59 is also in the sequence.
Since 59 is the seventeenth prime and the concatenation of 17 and 59 gives 1759, another prime, 59 is also in the sequence.
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| MATHEMATICA
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(*(* First run the program given for A154963*) *) Prime[A154963]
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| EXTENSIONS
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Edited and extended beyond a(3) by Alonso del Arte, Jan 20 2009, with thanks to _Klaus Brockhaus'_'s edit of A154963
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| STATUS
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approved
editing
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#4 by Charles R Greathouse IV at Fri Oct 12 14:38:24 EDT 2012
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| EXTENSIONS
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Edited and extended beyond a(3) by _Alonso del Delarte (alonso.delarte(AT)gmail.com), Arte_, Jan 20 2009, with thanks to Klaus Brockhaus's edit of A154963
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Discussion
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| Fri Oct 12
| 14:38
| OEIS Server: https://oeis.org/edit/global/1835
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#3 by Russ Cox at Fri Mar 30 18:52:32 EDT 2012
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| AUTHOR
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_Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), _, Jan 19 2009
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Discussion
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| Fri Mar 30
| 18:52
| OEIS Server: https://oeis.org/edit/global/257
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#2 by N. J. A. Sloane at Tue Jun 01 03:00:00 EDT 2010
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| NAME
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Primes n such that concatenation primeof ispi(n) and an concatenationis prime, with npi andbeing n-ththe prime counting function.
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| DATA
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3, 59, 83, 179, 283, 353, 431, 709, 1433, 2269, 2381, 3559, 3593, 4153, 5503, 6899, 7109, 7351, 7649, 8513, 11909, 13297, 14107, 14437, 14591, 16073, 16127, 16451, 16901, 17117, 17539, 17987, 18149, 19777, 20759, 21317, 22027, 24439, 25357, 26783, 27437, 29269, 30253, 32299, 34057, 34259, 34421, 34543, 35617, 36307, 37049
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| EXAMPLE
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IfSince 3 is the second n=2=prime number and 3=prime(2), thenthe concatenation of 23 = prime2 and 3=a(1). If gives 23, which is n=17=prime, 3 is in the andsequence. Since 59= is the seventeenth prime(17), then and the concatenation of 1759 = prime17 and 59=a(2). If n=23=primegives and1759, another 83=prime(23), then, 59 is concatenationalso 2383 = primein andthe 83=a(3), etcsequence.
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| MATHEMATICA
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(*First run the program given for A154963*) Prime[A154963]
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| CROSSREFS
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Cf. A000027, A000040.
pi(a(n)) = A154963.
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| KEYWORD
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nonn,uned,base,bref,new
nonn,base
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| EXTENSIONS
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Edited and extended beyond a(3) by Alonso Delarte (alonso.delarte(AT)gmail.com), Jan 20 2009, with thanks to Klaus Brockhaus's edit of A154963
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#1 by N. J. A. Sloane at Fri Feb 27 03:00:00 EST 2009
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| NAME
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Primes such that prime is a concatenation prime n and n-th prime.
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| DATA
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3, 59, 83
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| OFFSET
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1,1
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| EXAMPLE
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If n=2=prime and 3=prime(2), then concatenation 23 = prime and 3=a(1). If n=17=prime and 59=prime(17), then concatenation 1759 = prime and 59=a(2). If n=23=prime and 83=prime(23), then concatenation 2383 = prime and 83=a(3), etc.
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| CROSSREFS
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Cf. A000027, A000040.
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| KEYWORD
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nonn,uned,base,bref
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| AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jan 19 2009
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| STATUS
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approved
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