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A237580
a(n) = (2n)! - n! + 1.
3
1, 2, 23, 715, 40297, 3628681, 479000881, 87178286161, 20922789847681, 6402373705365121, 2432902008173011201, 1124000727777567763201, 620448401733238960358401, 403291461126605629356979201, 304888344611713860414325708801, 265252859812191058635000805632001
OFFSET
0,2
COMMENTS
Primes are listed in A118812, the corresponding indices in A237443; the least prime factor of a(n) in A237579.
LINKS
MATHEMATICA
Table[((2 n)! - n! + 1), {n, 0, 30}] (* Vincenzo Librandi, Feb 11 2014 *)
PROG
(PARI) A237580 = n->(2*n)!-n!+1
(Magma) [Factorial(2*n)-Factorial(n)+1: n in [0..15]]; // Vincenzo Librandi, Feb 11 2014
CROSSREFS
Cf. A000142 (n!), A010050 ((2n)!)
Sequence in context: A015098 A269021 A136039 * A273976 A098633 A015211
KEYWORD
nonn
AUTHOR
M. F. Hasler, Feb 09 2014
STATUS
approved