A093622 - OEIS

A093622

Largest prime of the form n!/k!-1.

5, 23, 59, 719, 5039, 6719, 181439, 5039, 6652799, 479001599, 154439, 87178291199, 54486431999, 3487131647999, 59281238015999, 1067062284287999, 1013709170073599, 405483668029439999, 39070079, 180503769599

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OFFSET

3,1

LINKS

Table of n, a(n) for n=3..22.

Dario Alpern, Factorization using the Elliptic Curve Method.

EXAMPLE

a(5) =59 because 5!/1!-1=119=7*17 is composite, whereas 5!/2!-1=59 is prime.

PROG

ECM, see link.

CROSSREFS

Cf. A093623 smallest k>0 such that n!/k!-1 is prime, A055490 primes of form n!-1, A093437 largest prime of the form n!/k!+1.

Sequence in context: A246607 A116581 A337750 * A089137 A361917 A362338

Adjacent sequences: A093619 A093620 A093621 * A093623 A093624 A093625

KEYWORD

nonn

AUTHOR

Hugo Pfoertner, Apr 06 2004

STATUS

approved