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 A159974 #6 Feb 09 2022 08:34:05 %S A159974 1,1,1,2,1,2,3,2,2,5,4,3,4,5,12,5,4,6,10,12,28,6,5,8,15,24,28,65,7,6, %T A159974 10,20,36,56,65,151,8,7,12,25,48,84,130,151,351,9,8,14,30,60,112,195, %U A159974 302,351,816,10,9,16,35,72,140,260,453,702,816,1897 %N A159974 Triangle read by rows, M * Q; M = an infinite lower triangular Toeplitz matrix with (1, 1, 2, 3, 4, 5, ...) in every column. Q = a matrix with A034943: (1, 1, 2, 5, 12, 28, ...) as the main diagonal and the rest zeros. %C A159974 Row sums = A034943 starting (1, 2, 5, 12, 28, 65, 151, 351, ...). %C A159974 As a property of eigentriangles, sum of n-th row terms = rightmost term of next row. %C A159974 A034943 starting (1, 2, 5, 12, 28, ...) = the INVERT transform of (1, 1, 2, 3, 4, 5, ...). %F A159974 Triangle read by rows, M * Q; M = an infinite lower triangular Toeplitz matrix with (1, 1, 2, 3, 4, 5, ...) in every column. Q = a matrix with A034943: (1, 1, 2, 5, 12, 28, ...) as the main diagonal and the rest zeros. %e A159974 First few rows of the triangle: %e A159974 1; %e A159974 1, 1; %e A159974 2, 1, 2; %e A159974 3, 2, 2, 5; %e A159974 4, 3, 4, 5, 12; %e A159974 5, 4, 6, 10, 12, 28; %e A159974 6, 5, 8, 15, 24, 28, 65; %e A159974 7, 6, 10, 20, 36, 56, 65, 151; %e A159974 8, 7, 12, 25, 48, 84, 130, 151, 351; %e A159974 9, 8, 14, 30, 60, 112, 195, 302, 351, 816; %e A159974 10, 9, 16, 35, 72, 140, 260, 453, 702, 816, 1897; %e A159974 ... %e A159974 Example: row 6 = (4, 3, 4, 5, 12) = termwise products of (1, 1, 2, 5, 12) and (4, 3, 2, 1, 1). %Y A159974 Cf. A034943. %K A159974 nonn,tabl %O A159974 2,4 %A A159974 _Gary W. Adamson_, Apr 28 2009