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 A102411 #19 Jun 16 2016 23:27:27 %S A102411 0,1,0,-16,5,1,0,5256,-3068,276,32,0,2070720,2367420,-912150,53220, %T A102411 3510,0,-36031524480,15327895296,-40587120,-387492840,21414120,758184, %U A102411 840,-212459319878400,-75473246681280,38182549456800,-2562251680800,-195611371200,13639812480,285616800,453600 %N A102411 Even triangle !n. This table read by rows gives the coefficients of sum formulas of n-th Left factorials (A003422). The k-th row (6>=k>=1) contains T(i,k) for i=1 to k+2, where k=[2*n+1+(-1)^(n-1)]/4 and T(i,k) satisfies !n = Sum_{i=1..k+2} T(i,k) * n^(i-1) / (2*k-2)!. %C A102411 The sum of signed coefficients for each k-th row is divisible by (2*k-2)!. Moreover, another variant (but an incomplete one, and sorted differently) of the above sequence is presented in A101752. %e A102411 Triangle starts: %e A102411 0, 1, 0; %e A102411 -16, 5, 1, 0; %e A102411 5256, -3068, 276, 32, 0; %e A102411 2070720, 2367420, -912150, 53220, 3510, 0; %e A102411 -36031524480, 15327895296, -40587120, -387492840, 21414120, 758184, 840; %e A102411 ... %e A102411 !11=4037914; substituting n=11 in the formula of the k-th row we obtain k=6 and the coefficients T(i,6) are those needed for computing !11. %e A102411 => !11 = [ -212459319878400 -75473246681280*11 +38182549456800*11^2 -2562251680800*11^3 -195611371200*11^4 +13639812480*11^5 +285616800*11^6 +453600*11^7 ]/10! = 4037914. %Y A102411 Cf. A102412, A094638, A094216, A003422, A008276, A101752, A102409, A102410, A101751, A000142, A101559, A101032, A099731. %K A102411 sign,tabf,uned %O A102411 1,4 %A A102411 _André F. Labossière_, Jan 07 2005