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 A134402 #25 Sep 01 2024 14:13:05
%S A134402 1,0,1,0,0,2,0,0,0,3,0,0,0,0,4,0,0,0,0,0,5,0,0,0,0,0,0,6,0,0,0,0,0,0,
%T A134402 0,7,0,0,0,0,0,0,0,0,8,0,0,0,0,0,0,0,0,0,9,0,0,0,0,0,0,0,0,0,0,10,0,0,
%U A134402 0,0,0,0,0,0,0,0,0,11,0,0,0,0,0,0,0,0,0,0,0,0,12,0,0,0,0,0,0,0,0,0,0,0,0,0,13
%N A134402 Triangle read by rows, for n > 0, n zeros followed by n.
%C A134402 Multiplied by the vector [1, 2, 3, ...] from the right gives (1, 2, 6, 12, 20, 30, 42, ...), A002378.
%C A134402 Triangle T(n,k), read by rows, given by [0,0,0,0,0,0,0,...] DELTA [1,1,-1,1,0,0,0,0,0,...] where DELTA is the operator defined in A084938. - _Philippe Deléham_, Oct 26 2007
%F A134402 Triangle read by rows, a(0) = 1, then for n > 0, n zeros followed by n. Infinite lower triangular matrix with (1, 1, 2, 3, 4, ...) in the main diagonal and the rest zeros.
%F A134402 G.f.: (1-x*y+x^2*y^2)/(-1+x*y)^2. - _R. J. Mathar_, Aug 11 2015
%e A134402 First few rows of the triangle:
%e A134402 1;
%e A134402 0, 1;
%e A134402 0, 0, 2;
%e A134402 0, 0, 0, 3;
%e A134402 0, 0, 0, 0, 4;
%e A134402 0, 0, 0, 0, 0, 5;
%e A134402 ...
%t A134402 Join[{1},Flatten[Table[PadLeft[{n},n+1,0],{n,15}]]] (* _Harvey P. Dale_, May 08 2012 *)
%Y A134402 Cf. A134403, A005449.
%Y A134402 Essentially the same as A130460.
%K A134402 nonn,easy,tabl
%O A134402 0,6
%A A134402 _Gary W. Adamson_, Oct 23 2007