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 A049191 #8 Jul 09 2025 03:53:31 %S A049191 1,4,7,49,376,886,28834,205195,190471228,326526374362,303663850108045, %T A049191 14055945960715098799,257290919119829489870640337, %U A049191 26045951636791617523077244751268466 %N A049191 Start with 1. Convert to base 3, describe it in base 3, convert to base 3. %e A049191 1->One 1->11->4; 4->11->Two 1's->21->7; 7->21->One 2, One 1->1211->49; etc. %Y A049191 Cf. A005150, A001388. %K A049191 nonn,base %O A049191 1,2 %A A049191 _Olivier Gérard_