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 A131110 #12 Oct 11 2021 18:43:50 %S A131110 1,3,1,6,3,1,10,6,5,1,15,10,15,5,1,21,15,35,15,7,1,28,21,70,35,28,7,1, %T A131110 36,28,126,70,84,28,9,1,45,36,210,126,210,84,45,9,1,55,45,330,210,462, %U A131110 210,165,45,11,1 %N A131110 A000012 * A133084. %C A131110 Row sums give A033484. %C A131110 Duplicate of A133093. - _Georg Fischer_, Oct 10 2021 %F A131110 A000012 * A133084 as infinite lower triangular matrices. %e A131110 First few rows of the triangle are: %e A131110 1; %e A131110 3, 1; %e A131110 6, 3, 1; %e A131110 10, 6, 5, 1; %e A131110 15, 10, 15, 5, 1; %e A131110 21, 15, 35, 15, 7, 1; %e A131110 28, 21, 70, 35, 28, 7, 1; %e A131110 ... %o A131110 (PARI) T4(n, k) = if(k == n, 1, (1 - (1 + (-1)^k)/2 )*binomial(n, k) + ((1 + (-1)^k)/2)*binomial(n - 1, k - 1)); \\ A133084 %o A131110 N=10; matrix(N, N, n, k, if(n>=k, 1))*matrix(N, N, n, k, T4(n,k)) \\ _Michel Marcus_, Oct 11 2021 %Y A131110 Cf. A133084, A033484. %K A131110 nonn,tabl %O A131110 1,2 %A A131110 _Gary W. Adamson_, Sep 08 2007 %E A131110 a(46) corrected by _Georg Fischer_, Oct 10 2021