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 A157497 #5 Jun 02 2025 01:25:09 %S A157497 1,1,2,1,0,3,1,4,0,4,1,0,0,0,5,1,6,9,0,0,6,1,0,0,0,0,0,7,1,8,0,16,0,0, %T A157497 0,8,1,0,18,0,0,0,0,0,9,1,10,0,0,25,0,0,0,0,10,1,0,0,0,0,0,0,0,0,0,11, %U A157497 1,12,30,40,0,36,0,0,0,0,0,12 %N A157497 Triangle read by rows, A156348 * A127648. %C A157497 Row sums = A157020: (1, 3, 4, 9, 6, 22, 8,...) %F A157497 Triangle read by rows, A156348 * A127648. A127648 = an infinite lower triangular matrix with (1, 2, 3,...) as the main diagonal and the rest zeros. %e A157497 First few rows of the triangle = %e A157497 1; %e A157497 1, 2; %e A157497 1, 0, 3; %e A157497 1, 4, 0, 4; %e A157497 1, 0, 0, 0, 5; %e A157497 1, 6, 9, 0, 0, 6; %e A157497 1, 0, 0, 0, 0, 0, 7; %e A157497 1, 8, 0, 16, 0, 0, 0, 8; %e A157497 1, 0, 18, 0, 0, 0, 0, 0, 9; %e A157497 1, 10, 0, 0, 25, 0, 0, 0, 0, 10; %e A157497 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11; %e A157497 1, 12, 30, 40, 0, 36, 0, 0, 0, 0, 0, 12; %e A157497 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13; %e A157497 1, 14, 0, 0, 0, 0, 49, 0, 0, 0, 0, 0, 0, 14; %e A157497 ... %e A157497 Row 4 = (1, 4, 0, 4) = termwise products of (1, 2, 0, 1) and (1, 2, 3, 4) %e A157497 where (1, 2, 0, 1) = row 4 of triangle A156348. %Y A157497 Cf. A156348, A126648, A156020 %K A157497 nonn,tabl %O A157497 1,3 %A A157497 _Gary W. Adamson_ & _Mats Granvik_, Mar 01 2009