This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A147304 #8 Jul 09 2018 23:19:59
%S A147304 28,17576,43308802158650,8610524734277600186228691452,
%T A147304 121374542758943982922417964798154019940274699584207321286055873543631298,
%U A147304 8126392396649531937838689708830356413772063825711016912849229977138431439363305375418692100492504264
%N A147304 a(n) = Sum_{k=1..prime(n)^2-1} binomial(2k,k).
%H A147304 D. Callan, <a href="https://www.jstor.org/stable/40391137">Divisibility of a Central Binomial Sum: Problem A11292 and A11307</a>, Amer. Math. Monthly, 116 (2009), 468-470.
%t A147304 Table[Sum[Binomial[2k,k],{k,Prime[n]^2-1}],{n,7}] (* _Harvey P. Dale_, Dec 26 2014 *)
%o A147304 (PARI) a(n) = sum(k=1, prime(n)^2-1, binomial(2*k,k)); \\ _Michel Marcus_, Jul 07 2018
%Y A147304 Cf. A146977, A066796, A147291.
%K A147304 nonn
%O A147304 1,1
%A A147304 _N. J. A. Sloane_, Apr 25 2009