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A231549 Least k>0 such that k!*n!+1 is a prime, or 0 if no such k exists. 2
1, 1, 1, 4, 2, 8, 3, 3, 3, 4, 1, 2, 3, 5, 8, 4, 10, 2, 11, 9, 5, 5, 7, 3, 14, 18, 1, 40, 24, 5, 5, 18, 8, 20, 2, 49, 1, 3, 5, 28, 1, 17, 38, 27, 11, 16, 10, 3, 24, 270, 2, 45, 2, 15, 175, 64, 17, 6, 4, 3, 8, 18, 13, 17, 65, 32, 12, 7, 72, 13, 21, 33, 1, 24, 36, 76, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Indices of 1's: A002981.

LINKS

Table of n, a(n) for n=1..77.

MATHEMATICA

Table[k = 1; While[! PrimeQ[k!*n! + 1], k++]; k, {n, 100}] (* T. D. Noe, Nov 18 2013 *)

CROSSREFS

Cf. A002981, A035093, A057217, A075757, A075758, A231901.

Sequence in context: A040015 A144926 A153016 * A088610 A026185 A026209

Adjacent sequences:  A231546 A231547 A231548 * A231550 A231551 A231552

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, Nov 15 2013

STATUS

approved

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Last modified June 24 22:04 EDT 2019. Contains 324337 sequences. (Running on oeis4.)