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 A107661 #5 Aug 16 2013 17:56:56 %S A107661 1,1,2,1,4,3,1,6,10,4,1,8,21,24,5,1,10,36,72,52,6,1,12,55,160,225,112, %T A107661 7,1,14,78,300,656,702,232,8,1,16,105,504,1525,2688,2133,480,9,1,18, %U A107661 136,784,3060,7750,10816,6480,976,10,1,20,171,1152,5537,18576,38875 %N A107661 Array read by antidiagonals: T(n,m) = Sum m^max(k,n-k),k=0..n. %F A107661 a(2n) = m^n(2(m^(n+1)-1)/(m-1)-1), a(2n+1) = 2m^(n+1)(m^(n+1)-1)/(m-1) %F A107661 T(5,m) = m^2*(2*m^2+2*m+1). - _R. J. Mathar_, Aug 16 2013 %e A107661 The array starts in row n=0 and column m=1 as: %e A107661 1, 1, 1, 1, 1, 1,... %e A107661 2, 4, 6, 8, 10, 12,... %e A107661 3, 10, 21, 36, 55, 78,... %e A107661 4, 24, 72, 160, 300, 504,... %e A107661 5, 52, 225, 656, 1525, 3060,... %e A107661 6, 112, 702, 2688, 7750,18576,... %e A107661 7, 232, 2133,10816,38875,111672,... %e A107661 8, 480, 6480,43520,195000,671328,... %Y A107661 Cf. A107659, A107660, A014105 (3rd row), A181617 (4th row) %K A107661 nonn,easy,tabl %O A107661 0,3 %A A107661 _Mitch Harris_