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 A113313 #13 Apr 17 2022 22:51:15 %S A113313 1,-2,1,0,-1,1,0,-1,0,1,0,-1,-1,1,1,0,-1,-2,0,2,1,0,-1,-3,-2,2,3,1,0, %T A113313 -1,-4,-5,0,5,4,1,0,-1,-5,-9,-5,5,9,5,1,0,-1,-6,-14,-14,0,14,14,6,1,0, %U A113313 -1,-7,-20,-28,-14,14,28,20,7,1,0,-1,-8,-27,-48,-42,0,42,48,27,8,1,0,-1,-9,-35 %N A113313 Riordan array (1-2x,x/(1-x)). %C A113313 Row sums are (1,-1,0,0,0,...) = 2*C(0,n) - C(1,n). %C A113313 Diagonal sums are -2*0^n - F(n-4) with g.f. (1 - 3x + 2x^2) / (1 - x - x^2). %C A113313 Inverse of A113310. %F A113313 T(n, k) = C(n-1, n-k) - 2*C(n-2, n-k-1). %F A113313 exp(x) * e.g.f. for row n = e.g.f. for diagonal n. For example, for n = 3 we have exp(x)*(-x + x^3/3!) = -x - 2*x^2/2! - 2*x^3/3! + 5*x^5/5! + .... The same property holds more generally for Riordan arrays of the form ( f(x), x/(1 - x) ). - _Peter Bala_, Dec 21 2014 %e A113313 The triangle T(n, k) begins: %e A113313 n\k 0 1 2 3 4 5 6 7 8 9 10 ... %e A113313 0: 1 %e A113313 1: -2 1 %e A113313 2: 0 -1 1 %e A113313 3: 0 -1 0 1 %e A113313 4: 0 -1 -1 1 1 %e A113313 5: 0 -1 -2 0 2 1 %e A113313 6: 0 -1 -3 -2 2 3 1 %e A113313 7: 0 -1 -4 -5 0 5 4 1 %e A113313 8: 0 -1 -5 -9 -5 5 9 5 1 %e A113313 9: 0 -1 -6 -14 -14 0 14 14 6 1 %e A113313 10: 0 -1 -7 -20 -28 -14 14 28 20 7 1 %e A113313 ... Reformatted. - _Wolfdieter Lang_, Jan 06 2015 %Y A113313 Cf. A113310. %K A113313 easy,sign,tabl %O A113313 0,2 %A A113313 _Paul Barry_, Oct 25 2005