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A247044 Least number k > 0 such that k!*n! - 1 is prime. 0
3, 2, 1, 1, 2, 1, 1, 3, 6, 7, 14, 1, 8, 1, 2, 4, 2, 5, 16, 26, 27, 2, 18, 29, 9, 15, 7, 2, 24, 1, 44, 1, 1, 209, 12, 128, 20, 1, 18, 5, 6, 3, 21, 5, 42, 6, 45, 19, 14, 10, 8, 20, 72, 8, 226, 11, 5, 77, 99, 28, 16, 15, 157, 9, 24, 17, 110, 9, 28, 26, 16, 37, 163, 79, 29, 45, 58, 21, 66 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a(n) = K, a(K) <= n for all n.

a(n) = 1 if and only if n is in A002982.

LINKS

Table of n, a(n) for n=1..79.

PROG

(PARI)

a(n)=k=1; while(!ispseudoprime(k!*n!-1), k++); k

n=1; while(n<100, print1(a(n), ", "); n++)

CROSSREFS

Cf. A002982, A231549.

Sequence in context: A292068 A140056 A240239 * A083663 A085427 A172130

Adjacent sequences:  A247041 A247042 A247043 * A247045 A247046 A247047

KEYWORD

nonn

AUTHOR

Derek Orr, Sep 10 2014

STATUS

approved

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Last modified October 27 23:26 EDT 2020. Contains 338047 sequences. (Running on oeis4.)