A147304 a(n) = Sum_{k=1..prime(n)^2-1} binomial(2k,k).

28, 17576, 43308802158650, 8610524734277600186228691452, 121374542758943982922417964798154019940274699584207321286055873543631298, 8126392396649531937838689708830356413772063825711016912849229977138431439363305375418692100492504264

Offset: 1

Author

N. J. A. Sloane, Apr 25 2009

Keywords

• nonn

Links

• D. Callan, Divisibility of a Central Binomial Sum: Problem A11292 and A11307, Amer. Math. Monthly, 116 (2009), 468-470.

Crossrefs

Cf. A146977, A066796, A147291.

Programs

Mathematica

Table[Sum[Binomial[2k,k],{k,Prime[n]^2-1}],{n,7}] (* Harvey P. Dale, Dec 26 2014 *)

PARI

a(n) = sum(k=1, prime(n)^2-1, binomial(2*k,k)); \\ Michel Marcus, Jul 07 2018