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 A213953 #13 Jul 21 2015 05:33:54 %S A213953 1,-1,1,0,-1,1,1,-1,-1,1,1,1,-2,-1,1,-2,5,0,-3,-1,1,-9,5,10,-2,-4,-1, %T A213953 1,-9,-21,25,15,-5,-5,-1,1,50,-105,-11,62,19,-9,-6,-1,1,267,-141,-301, %U A213953 56,119,21,-14,-7,-1,1,413,777 %N A213953 Triangle by rows, inverse of A208891. %F A213953 Inverse of triangle A208891, Pascal's triangle matrix with an appended right border of 1's. %e A213953 Triangle starts: %e A213953 1; %e A213953 -1, 1 %e A213953 0, -1, 1 %e A213953 1, -1, -1, 1; %e A213953 1, 1, -2, -1, 1; %e A213953 -2, 5, 0, -3, -1, 1; %e A213953 -9, 5, 10, -2, -4, -1, 1; %e A213953 -9, -21, 25, 15, -5, -5, -1, 1; %e A213953 50, -105, -11, 62, 19, -9, -6, -1, 1; %e A213953 267, -141, -301, 56, 119, 21, -14, -7, -1, 1; %e A213953 413, 777, -1040, -566, 226, 198, 20, -20, -8, -1, 1; %e A213953 ... %p A213953 A208891 := proc(n,k) %p A213953 if n <0 or k<0 or k>n then %p A213953 0; %p A213953 elif n = k then %p A213953 1 ; %p A213953 else %p A213953 binomial(n-1,k) ; %p A213953 end if; %p A213953 end proc: %p A213953 A259456 := proc(n) %p A213953 local A, row, col ; %p A213953 A := Matrix(n, n) ; %p A213953 for row from 1 to n do %p A213953 for col from 1 to n do %p A213953 A[row, col] := A208891(row-1,col-1) ; %p A213953 end do: %p A213953 end do: %p A213953 LinearAlgebra[MatrixInverse](A) ; %p A213953 end proc: %p A213953 A259456(20) ; # _R. J. Mathar_, Jul 21 2015 %Y A213953 Cf. A208891, A000587 (first column), A014619 (2nd column), A080956 (4th subdiagonal). %K A213953 tabl,sign %O A213953 0,13 %A A213953 _Gary W. Adamson_, Jun 26 2012