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 A365747 #16 Dec 06 2023 14:25:09 %S A365747 2,2,8,1,4,3,7,4,1,4,0,5,3,4,2,4,4,1,5,2,7,1,7,7,2,7,2,8,5,9,1,6,5,0, %T A365747 7,6,0,7,3,3,3,8,8,4,5,2,6,6,1,0,1,1,8,2,7,9,7,2,9,3,1,7,6,7,1,7,2,4, %U A365747 0,7,2,3,2,2,1,9,0,5,9,5,0,8,9,7,1,0,3,6,8,1,7,8,9,2,2,8,7,9,3,3,4,8,2,7,7,7,3,0,1,7,7 %N A365747 Decimal expansion of Trinv(1 + Trinv(2 + Trinv(3 + Trinv(4 + ... )))) where Trinv(n) = (sqrt(8*n+1)-1)/2. %C A365747 Trinv(n) = (sqrt(8*n+1)-1)/2 is the inverse of A000217. %e A365747 2.2814374140534244152717727285916507607333884526610... %t A365747 TriangleRoot[n_] =(-1 + Sqrt[1 + 8 n])/2; RealDigits[ Fold[ TriangleRoot[ #1 + #2] &, 0, Reverse[ Range[200]]], 10,111][[1]] %Y A365747 Cf. A072449 (analog for square root), A099874 (analog for cube root). %Y A365747 Cf. A000217 (triangular numbers), A003056. %K A365747 nonn,cons %O A365747 1,1 %A A365747 _Kelvin Voskuijl_, Sep 17 2023