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 A128132 #22 Jul 27 2020 04:58:55 %S A128132 1,-1,2,0,-1,3,0,0,-1,4,0,0,0,-1,5,0,0,0,0,-1,6,0,0,0,0,0,-1,7,0,0,0, %T A128132 0,0,0,-1,8,0,0,0,0,0,0,0,-1,9,0,0,0,0,0,0,0,0,-1,10,0,0,0,0,0,0,0,0, %U A128132 0,-1,11,0,0,0,0,0,0,0,0,0,0,-1,12 %N A128132 A natural number transform, companion to A127701. %C A128132 Binomial transform is A128133. %F A128132 T(n,n) = n. %F A128132 T(n,n-1) = -1. %F A128132 T(n,k) = 0 for k <> n, n-1. %e A128132 Triangle T(n,k) (with rows n >= 1 and columns k = 1..n) begins: %e A128132 1; %e A128132 -1, 2; %e A128132 0, -1, 3; %e A128132 0, 0, -1, 4; %e A128132 0, 0, 0, -1, 5; %e A128132 0, 0, 0, 0, -1, 6; %e A128132 ... %p A128132 A128132 := proc(n,k) %p A128132 if n = k then %p A128132 n; %p A128132 elif k = n-1 then %p A128132 -1 ; %p A128132 else %p A128132 0 ; %p A128132 end if; %p A128132 end proc: # _R. J. Mathar_, Apr 26 2016 %t A128132 {1}~Join~Table[PadLeft[{-1, n}, n], {n, 2, 12}] // Flatten (* _Michael De Vlieger_, Apr 26 2016 *) %Y A128132 Cf. A127701, A128133, A128134. %K A128132 tabl,sign,easy %O A128132 1,3 %A A128132 _Gary W. Adamson_, Feb 15 2007