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 A199856 #9 Aug 11 2015 04:56:40 %S A199856 1,-1,1,-2,1,1,-4,1,2,1,-8,0,4,3,1,-16,-4,7,8,4,1,-32,-16,10,19,13,5, %T A199856 1,-64,-48,8,41,37,19,6,1,-128,-128,-16,80,96,62,26,7,1,-256,-320, %U A199856 -112,136,231,183,95,34,8,1,-512,-768,-416,176,518,501,311,137,43,9,1 %N A199856 Triangle T(n,k), read by rows, given by (-1,3,0,0,0,0,0,0,0,0,0,...) DELTA (1,0,-1/3,1/3,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938. %C A199856 Diagonal sums are in A199853, row sums are in A000007. %F A199856 T(n,k)=2*T(n-1,k)+T(n-1,k-1)-T(n-2,k-1), for n>2. %F A199856 T(n,0)=-2^(n-1) for n>0. %F A199856 T(2*n,n)=A047781(n) for n>0. %F A199856 T(n,1)=(4-n)*2^(n-3) for n>1. %F A199856 G.f.: (1-3*x+x^2*y)/(1-2*x+x^2*y-x*y). - _R. J. Mathar_, Aug 11 2015 %e A199856 Triangle begins : %e A199856 1 %e A199856 -1, 1 %e A199856 -2, 1, 1 %e A199856 -4, 1, 2, 1 %e A199856 -8, 0, 4, 3, 1 %e A199856 -16, -4, 7, 8, 4, 1 %e A199856 -32, -16, 10, 19, 13, 5, 1 %e A199856 -64, -48, 8, 41, 37, 19, 6, 1 %e A199856 -128, -128, -16, 80, 96, 62, 26, 7, 1 %Y A199856 Cf. A000012, A000079 %K A199856 sign,tabl %O A199856 0,4 %A A199856 _Philippe Deléham_, Nov 11 2011