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 A134833 #9 Nov 11 2016 21:48:51
%S A134833 1,-1,1,0,-2,12,-16,144,368,4768,39488,412288,4577280,55671808,
%T A134833 731390976,10335518720,156303439872,2518984822784,43099089166336,
%U A134833 780268880543744,14902336357040128,299452809649520640,6315501510334480384,139485953831272710144,3219718099932104622080
%N A134833 Alternating row sums of triangle A134832.
%H A134833 G. C. Greubel, <a href="/A134833/b134833.txt">Table of n, a(n) for n = 0..449</a>
%F A134833 a(n) = Sum_{k=0..n} A134832(n,k)*(-1)^k for n>=0.
%t A134833 A000757[n_] := (-1)^n + Sum[(-1)^k*n!/((n - k)*k!), {k, 0, n - 1}]; a[n_, n_] = 1; a[n_, 0] := A000757[n]; a[n_, k_] := a[n, k] = n/k*a[n - 1, k - 1]; Table[Sum[a[n, k]*(-1)^k, {k, 0, n}], {n, 0, 10}] (* _G. C. Greubel_, Nov 10 2016 *)
%Y A134833 Cf. A000142 (factorials as row sums of triangle A134832).
%K A134833 sign,easy
%O A134833 0,5
%A A134833 _Wolfdieter Lang_, Jan 21 2008