

A137390


Numbers k for which (9 + k!)/9 is prime.


50



8, 46, 87, 168, 259, 262, 292, 329, 446, 1056, 3562, 11819, 26737
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

No other k exists, for k <= 6000.  Dimitris Zygiridis (dmzyg70(AT)gmail.com), Jul 25 2008
The next number in the sequence, if one exists, is greater than 10944.  Robert Price, Mar 16 2010
Borrowing from A139074 another term in this sequence is 26737. There may be others between 10944 and 26737.  Robert Price, Dec 13 2011
There are no other terms for k < 26738.  Robert Price, Feb 10 2012


LINKS

Table of n, a(n) for n=1..13.


EXAMPLE

a(11) = 3562 because 3562 is the 11th natural number for which k!/9 + 1 is prime. 3562 is the new term.


MATHEMATICA

a = {}; Do[If[PrimeQ[(n! + 9)/9], AppendTo[a, n]], {n, 1, 500}]; a


PROG

(PARI) for(n=6, 1e4, if(ispseudoprime(n!/9+1), print1(n", "))) \\ Charles R Greathouse IV, Jul 15 2011
(PFGW) ABC2 $a!/9+1
a: from 6 to 1000 // Jinyuan Wang, Feb 04 2020


CROSSREFS

Cf. A139068 (primes of the form (9 + k!)/9).
Cf. k!/m  1 is a prime: A002982, A082671, A139056, A139199A139205.
Cf. (m + k!)/m is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A139071.
Sequence in context: A328198 A340975 A213132 * A190048 A034469 A212673
Adjacent sequences: A137387 A137388 A137389 * A137391 A137392 A137393


KEYWORD

nonn,more


AUTHOR

Artur Jasinski, Apr 09 2008


EXTENSIONS

Edited by N. J. A. Sloane, May 15 2008 at the suggestion of R. J. Mathar
a(10) corrected from 1053 to 1056 by Dmitry Kamenetsky, Jul 12 2008
a(11) from Dimitris Zygiridis (dmzyg70(AT)gmail.com), Jul 25 2008
a(12)a(13) from Robert Price, Feb 10 2012


STATUS

approved



