A060842 a(n) = (binomial(2*p,p)-2)/p^2 where p = prime(n).

1, 2, 10, 70, 5830, 61542, 8074762, 97909318, 15564141262, 35751803209918, 484316704740126, 1275478863649106070, 252697549582862416198, 3589806968644540547902, 735944382229592689247902, 2233009988826006212007799102, 6997040996166222103946741339278, 103007775714125517422789307317230

Offset

1,2

Links

Harry J. Smith, Table of n, a(n) for n = 1..100

Formula

a(n) = A177454(n)/A000040(n). - R. J. Mathar, Jan 09 2017

Mathematica

Table[(Binomial[2p, p]-2)/p^2, {p, Prime[Range[20]]}] (* Harvey P. Dale, Mar 05 2023 *)

Prog

(PARI) a(n) = { my(p=prime(n)); (binomial(2*p, p) - 2)/p^2 } \\ Harry J. Smith, Jul 19 2009

Crossrefs

Sequence in context: A118748 A118752 A362821 * A245834 A271214 A366241

Adjacent sequences: A060839 A060840 A060841 * A060843 A060844 A060845

Keyword

nonn,changed

Author

Benoit Cloitre, Feb 13 2003

Status

approved