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%I #6 Oct 16 2014 11:54:11
%S 2,14,134,1814,32054,697334,17994614,536913014,18180138614,
%T 688622711414,28847210769014,1324142261418614,66088894793898614,
%U 3563385531547818614,206406590463275178614,12782685296230371498614,842817079876858728618614
%N Sum_{i=1..n} (2i)!/i!.
%C a(n) = 4 mod 10 for n>1.
%H Harvey P. Dale, <a href="/A111424/b111424.txt">Table of n, a(n) for n = 1..366</a>
%F a(n) ~ 2^(2*n+1/2) * n^n / exp(n). - _Vaclav Kotesovec_, Oct 16 2014
%e a(3) = 2!/1! + 4!/2! + 6!/3! = 2 + 12 + 120 = 134.
%t Accumulate[Table[(2i)!/i!,{i,20}]] (* _Harvey P. Dale_, Jul 06 2014 *)
%K nonn
%O 1,1
%A _Jon Perry_, Nov 13 2005