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 A134394 #15 Jun 01 2022 08:16:07 %S A134394 1,2,1,3,3,1,4,6,4,1,5,10,9,5,1,6,15,16,12,6,1,7,21,25,22,15,7,1,8,28, %T A134394 36,35,28,18,8,1,9,36,49,51,45,34,21,9,1,10,45,64,70,66,55,40,24,10,1, %U A134394 11,55,81,92,91,81,65,46,27,11,1,12,66,100,117,120,112,96,75,52,30,12,1,13,78,121,145,153 %N A134394 Triangle T(n,k) = Sum_{j=k..n} A077028(j,k), read by rows. %C A134394 Row sums = A055795: (1, 3, 7, 15, 30, 56, 98, ...). %C A134394 Antidiagonal reading of A139600 without its left column. - _R. J. Mathar_, Apr 17 2011 %F A134394 A000012 * A077028 as infinite lower triangular matrices. %F A134394 T(n,k) = (k-n-1)*(k*(k-n)-2)/2. - _R. J. Mathar_, Apr 17 2011 %e A134394 First few rows of the triangle: %e A134394 1; %e A134394 2, 1; %e A134394 3, 3, 1; %e A134394 4, 6, 4, 1; %e A134394 5, 10, 9, 5, 1; %e A134394 6, 15, 16, 12, 6, 1; %e A134394 7, 21, 25, 22, 15, 7, 1; %p A134394 A077028 := proc(n,k) if n < 0 or k<0 or k > n then 0; else k*(n-k)+1 ; end if; end proc: %p A134394 A134394 := proc(n,k) add ( A077028(j,k),j=k..n) ; end proc: %p A134394 seq(seq(A134394(n,k),k=0..n),n=0..15) ; # _R. J. Mathar_, Apr 17 2011 %Y A134394 Cf. A077028, A055795, A139600. %K A134394 nonn,tabl %O A134394 1,2 %A A134394 _Gary W. Adamson_, Oct 23 2007