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 A373009 #21 Jun 11 2024 10:14:07 %S A373009 1,5,4,7,1,5,7,5,8,7,2,9,7,8,7,6,6,6,1,2,5,8,8,0,7,9,4,0,0,8,6,5,1,8, %T A373009 4,8,3,6,2,0,6,4,1,3,1,3,4,6,8,5,0,5,1,3,4,9,8,1,6,5,8,8,4,7,3,3,8,7, %U A373009 5,9,7,9,8,0,1,1,1,2,3,0,3,5,2,6,4,5,7,3,6,5,5,3,1,5,8,0,7,3,4,9,4,2,9,6,0,1,6,4,7,7,7 %N A373009 Decimal expansion of PentInv(1 + PentInv(2 + PentInv(3 + PentInv(4 + ... )))) where PentInv(n) = (1 + sqrt(1 + 24*n))/6. %C A373009 The inverse of the pentagonal numbers is defined here as (1 + sqrt(1 + 24*n))/6. %e A373009 1.54715758729787666125880794008651848362064131346850513... %Y A373009 Cf. A365747 (triangular inverse), A072449 (square root), A099874 (cubes). %Y A373009 Cf. A000326 (pentagonal numbers). %K A373009 nonn,cons %O A373009 1,2 %A A373009 _Kelvin Voskuijl_, May 22 2024