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%I A147291 #8 Jun 07 2019 10:31:48
%S A147291 0,28,17576,209295260,43308802158650,150315393336149895056,
%T A147291 8610524734277600186228691452,8068213695203463278728832778415607708,
%U A147291 122985780058082302876789680971972469134558550878,30386103720799858392019761983012781659021124133753353112778
%N A147291 a(n) = Sum_{k=1..n^2-1} binomial(2k,k).
%H A147291 D. Callan, <a href="https://www.jstor.org/stable/40391137">Divisibility of a Central Binomial Sum: A11292 and A11307</a>, Amer. Math. Monthly, 116 (2009), 468-470.
%F A147291 a(n) ~ 4^(n^2) / (3*sqrt(Pi)*n). - _Vaclav Kotesovec_, Jun 07 2019
%t A147291 Table[Sum[Binomial[2*k, k], {k, 1, n^2 - 1}], {n, 1, 10}] (* _Vaclav Kotesovec_, Jun 07 2019 *)
%o A147291 (PARI) a(n) = sum(k=1, n^2-1, binomial(2*k,k)); \\ _Michel Marcus_, Jul 05 2018
%Y A147291 Cf. A146977, A066796, A147304.
%K A147291 nonn
%O A147291 1,2
%A A147291 _N. J. A. Sloane_, Apr 25 2009

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