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 A130297 #7 Nov 09 2024 11:36:27 %S A130297 1,4,1,8,2,1,13,3,2,1,19,4,3,2,1,26,5,4,3,2,1,34,6,5,4,3,2,1,43,7,6,5, %T A130297 4,3,2,1,53,8,7,6,5,4,3,2,1,64,9,8,7,6,5,4,3,2,1 %N A130297 A130296^2. %C A130297 Left border = A034856: (1, 4, 8, 13, 19, 26, 34, ...). %C A130297 Row sums = A028387: (1, 5, 11, 19, 29, 41, 55, ...). %F A130297 Square of A130296 as an infinite lower triangular matrix. %e A130297 First few rows of the triangle: %e A130297 1; %e A130297 4, 1; %e A130297 8, 2, 1; %e A130297 13, 3, 2, 1; %e A130297 19, 4, 3, 2, 1; %e A130297 26, 5, 4, 3, 2, 1; %e A130297 ... %o A130297 (Python) %o A130297 from math import comb, isqrt %o A130297 def A130297(n): return (a:=comb(r:=(m:=isqrt(k:=n<<1))+(k>m*(m+1))+1,2))+1-n+(a-1 if ((k2:=n-1<<1)==(m2:=isqrt(k2))*(m2+1)) else 0) # _Chai Wah Wu_, Nov 09 2024 %Y A130297 Cf. A130296, A034856, A028387. %K A130297 nonn,tabl %O A130297 1,2 %A A130297 _Gary W. Adamson_, May 20 2007