The On-Line Encyclopedia of Integer Sequences (OEIS)

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A142863

Semiprimes n (A001358) for which A000001(n) is 2.
(history; published version)

#9 by Joerg Arndt at Wed Mar 15 11:11:43 EDT 2023

STATUS

reviewed

approved

#8 by Andrew Howroyd at Wed Mar 15 11:11:23 EDT 2023

STATUS

proposed

reviewed

#7 by Michel Marcus at Wed Mar 15 11:07:09 EDT 2023

STATUS

editing

proposed

#6 by Michel Marcus at Wed Mar 15 11:07:07 EDT 2023

COMMENTS

Semiprimes p^2 or pq with p<q and gcd(p,q-1)=p. - _T. D. Noe, _, Oct 08 2008

CROSSREFS

Cf. A000001, A001358.

STATUS

approved

editing

#5 by Russ Cox at Fri Mar 30 17:39:39 EDT 2012

EXTENSIONS

More terms from _R. J. Mathar (mathar(AT)strw.leidenuniv.nl), _, Oct 04 2008

Discussion

Fri Mar 30

17:39

OEIS Server: https://oeis.org/edit/global/190

#4 by Russ Cox at Fri Mar 30 16:50:58 EDT 2012

AUTHOR

_N. J. A. Sloane (njas(AT)research.att.com), _, Oct 03 2008

Discussion

Fri Mar 30

16:50

OEIS Server: https://oeis.org/edit/global/110

#3 by N. J. A. Sloane at Thu Nov 11 07:34:06 EST 2010

LINKS

T. D. Noe, <a href="/A142863/b142863.txt">Table of n, a(n) for n=1..1000</a>

KEYWORD

nonn,new

nonn

#2 by N. J. A. Sloane at Fri Feb 27 03:00:00 EST 2009

LINKS

T. D. Noe, <a href="http://www.research.att.com/~njas/sequences/b142863.txt">Table of n, a(n) for n=1..1000</a>

KEYWORD

nonn,new

nonn

AUTHOR

N. J. A. Sloane (njas, (AT)research.att.com), Oct 03 2008

#1 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009

NAME

Semiprimes n (A001358) for which A000001(n) is 2.

DATA

4, 6, 9, 10, 14, 21, 22, 25, 26, 34, 38, 39, 46, 49, 55, 57, 58, 62, 74, 82, 86, 93, 94, 106, 111, 118, 121, 122, 129, 134, 142, 146, 155, 158, 166, 169, 178, 183, 194, 201, 202, 203, 205, 206, 214, 218, 219, 226, 237, 253, 254, 262, 274, 278, 289, 291, 298, 301

OFFSET

1,1

COMMENTS

Semiprimes p^2 or pq with p<q and gcd(p,q-1)=p. - T. D. Noe, Oct 08 2008

LINKS

T. D. Noe, <a href="http://www.research.att.com/~njas/sequences/b142863.txt">Table of n, a(n) for n=1..1000</a>

John H. Conway, Heiko Dietrich and E. A. O'Brien, <a href="http://www.math.auckland.ac.nz/~obrien/research/gnu.pdf">Counting groups: gnus, moas and other exotica</a>.

KEYWORD

nonn

AUTHOR

njas, Oct 03 2008

EXTENSIONS

More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 04 2008

STATUS

approved