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A085747 Least positive k such that n!+k is a semiprime. 4
3, 2, 3, 1, 1, 1, 1, 1, 5, 1, 3, 17, 1, 1, 7, 2, 3, 23, 1, 1, 11, 29, 3, 1, 1, 1, 37, 1, 41, 2, 19, 11, 11, 1, 7, 3, 41, 1, 13, 127, 47, 59, 2, 37, 5, 37, 59, 1, 2, 73, 59, 79, 73, 1, 1, 61, 118, 37, 1, 61, 31, 37, 43, 7, 83, 71, 19, 7, 103, 19, 1, 107, 37, 167, 1, 103, 3, 73, 109, 97 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Sequence entries must be 1 or a prime.

LINKS

Dario Alejandro Alpern, Factorization using the Elliptic Curve Method

Hisanori Mishima, Factorization of n! + 1 (n = 1 to 100)

MATHEMATICA

PrimeFactors[n_Integer] := Flatten[ Table[ # [[1]], { # [[2]]}] & /@ FactorInteger[n]];

CROSSREFS

Cf. A089538, A089539, A089540, A089541.

Sequence in context: A166592 A103497 A191390 * A106693 A107335 A200223

Adjacent sequences:  A085744 A085745 A085746 * A085748 A085749 A085750

KEYWORD

nonn

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Jul 21 2003

EXTENSIONS

Extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 27 2003

a(55) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 09 2003

More terms from Sean A. Irvine (sairvin(AT)xtra.co.nz), Mar 29 2010

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Last modified February 14 11:32 EST 2012. Contains 205623 sequences.