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#16 by Michel Marcus at Sat Apr 13 11:25:24 EDT 2019
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#15 by Joerg Arndt at Sat Apr 13 11:01:14 EDT 2019
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#14 by Jon E. Schoenfield at Sat Apr 13 10:43:09 EDT 2019
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#13 by Jon E. Schoenfield at Sat Apr 13 10:43:06 EDT 2019
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| NAME
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Numbers such that the sum of theirwhose even divisors is 2 times a prime.
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| COMMENTS
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(See A195268 with, which has similar properties)..)
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| FORMULA
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Conjecture: a(n) = 2*A023194(n). - ). - _R. J. Mathar, _, Sep 15 2011
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| EXAMPLE
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The divisors of 18 are { {1, 2, 3, 6, 9, 18}, and half the sum of the even divisors is (2 + 6 + 18)/2 = 26/2 = 13 , which is prime. Hence 18 is in the sequence.
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| MAPLE
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for n from 1 do if isA195334(n) then print(n); end if; end do: # : # _R. J. Mathar, _, Sep 15 2011
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| STATUS
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approved
editing
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#12 by Charles R Greathouse IV at Thu Nov 21 12:50:20 EST 2013
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| MATHEMATICA
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Select[Range[2000000], PrimeQ[Total[Select[Divisors[#], EvenQ]]/2]&] (* From ]&] (* _Harvey P. Dale, _, Mar 07 2012 *)
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Discussion
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| Thu Nov 21
| 12:50
| OEIS Server: https://oeis.org/edit/global/2062
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#11 by Russ Cox at Fri Mar 30 18:35:59 EDT 2012
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| AUTHOR
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_Michel Lagneau (mn.lagneau2(AT)orange.fr), _, Sep 15 2011
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Discussion
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| Fri Mar 30
| 18:35
| OEIS Server: https://oeis.org/edit/global/205
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#10 by Harvey P. Dale at Wed Mar 07 17:05:12 EST 2012
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#9 by Harvey P. Dale at Wed Mar 07 17:05:08 EST 2012
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| MATHEMATICA
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Select[Range[2000000], PrimeQ[Total[Select[Divisors[#], EvenQ]]/2]&] (* From Harvey P. Dale, Mar 07 2012 *)
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| STATUS
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approved
editing
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#8 by T. D. Noe at Thu Sep 15 19:31:03 EDT 2011
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#7 by Michel Lagneau at Thu Sep 15 16:31:34 EDT 2011
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