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 A143864 #8 Apr 18 2013 11:25:53 %S A143864 1,4,1,9,4,5,16,9,20,18,25,16,45,72,63,36,25,80,162,252,221,49,36,125, %T A143864 288,567,884,776,64,49,180,450,1008,1989,3104,2725,81,64,245,648,1575, %U A143864 3536,6984,10900,9569 %N A143864 Eigentriangle of A055461 (square subsequences decrescendo). %C A143864 Row sums A033453: (1, 5, 18, 63, 221, 776, 2725,...); the shifted right border. Sum of row n terms = rightmost term of next row. %F A143864 A055461 (squares decrescendo triangle) * (A033453 * 0^(n-k)); 1<=k<=1; where (A033453 * 0^(n-k)) = an infinite lower triangular matrix with the INVERT transform of the squares as the main diagonal, starting: (1, 1, 5, 18, 63, 221, 776,...) and the rest zeros. %e A143864 First few rows of the triangle = %e A143864 1; %e A143864 4, 1; %e A143864 9, 4, 5; %e A143864 16, 9, 20, 18; %e A143864 25, 16, 45, 72, 63; %e A143864 36, 25, 80, 162, 252, 221; %e A143864 49, 36, 125, 288, 567, 884, 776; %e A143864 ... %e A143864 Row 3 = (9, 4, 5) = termwise product of (9, 4, 1) and (1, 1, 5) (9*1, 4*1, 1*5). %Y A143864 Cf. A055461, A033453. %K A143864 nonn,tabl %O A143864 1,2 %A A143864 _Gary W. Adamson_, Sep 04 2008