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A137390 Numbers n for which n!/9 + 1 is prime. 51
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

For primes of the form (9+k!)/9 see A139068

a(10) corrected from 1053 to 1056 by Dmitry Kamenetsky, Jul 12 2008

No other n exists, for n<= 6000. - Dimitris Zygiridis (dmzyg70(AT)gmail.com), Jul 25 2008

The next number in the sequence, if one exists is >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 n < 26738. - Robert Price, Feb 10 2011

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

CROSSREFS

Cf. A082672, A089085, A089130, A117141, A007749, A139056, A139057, A139058, A139059, A139060, A139061, A139061, A139062, A139063, A139064, A139065, A139066, A020458, A139068, A137390, A139070, A139071, A139072.

Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199-A139205; n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071 (1<=m<=10).

Sequence in context: A296945 A328198 A213132 * A190048 A034469 A212673

Adjacent sequences:  A137387 A137388 A137389 * A137391 A137392 A137393

KEYWORD

nonn

AUTHOR

Artur Jasinski, Apr 09 2008

EXTENSIONS

Edited by N. J. A. Sloane, May 15 2008 at the suggestion of R. J. Mathar

3562 from Dimitris Zygiridis (dmzyg70(AT)gmail.com), Jul 25 2008

11819 and 26737 from Robert Price, Feb 10 2012

STATUS

approved

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Last modified October 18 14:52 EDT 2019. Contains 328161 sequences. (Running on oeis4.)