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%I #25 Jun 24 2022 19:59:13
%S 1,3,27,747,41067,3669867,482671467,87660962667,21010450850667,
%T 6423384156578667,2439325392333218667,1126440053169940898667,
%U 621574841786409380258667,403913035968392044964258667
%N a(n) = Sum_{k=0..n} (2*k)!.
%C Last digit is 7 for n > 2. Therefore there is no square in this sequence except 1. - _Altug Alkan_, Dec 01 2015
%H G. C. Greubel, <a href="/A138525/b138525.txt">Table of n, a(n) for n = 0..224</a>
%p A138525:=n->add((2*k)!, k=0..n): seq(A138525(n), n=0..15); # _Wesley Ivan Hurt_, Dec 01 2015
%t Table[Sum[(2i)!, {i, 0, n}], {n, 0, 15}] (* _Stefan Steinerberger_, Mar 25 2008 *)
%o (PARI) a(n) = sum(k=0, n, (2*k)!); \\ _Altug Alkan_, Dec 01 2015
%Y Cf. A138523, A138524.
%Y Partial sums of A010050.
%K easy,nonn
%O 0,2
%A _Leroy Quet_, Mar 23 2008
%E More terms from _Stefan Steinerberger_ and _Robert G. Wilson v_, Mar 25 2008
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