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

Author

Benoit Cloitre, Feb 13 2003

Keywords

• nonn

Links

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

Programs

Mathematica

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

PARI

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

Formula

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