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 A031156 #13 Jul 08 2025 19:35:38 %S A031156 1,16,128,8192,16384,262144,16777216,134217728,2147483648,17179869184, %T A031156 137438953472,562949953421312,2251799813685248,147573952589676412928, %U A031156 4722366482869645213696,75557863725914323419136,151115727451828646838272,2417851639229258349412352,77371252455336267181195264,680564733841876926926749214863536422912 %N A031156 a(n) = 2^A031142(n). %C A031156 Powers of 2 such that there is an increasing number of nonzero digits after the rightmost digit 0, including a leading 0. a(20)=2^129 is the first term where the rightmost 0 is not the leading 0. - _Hugo Pfoertner_, Apr 12 2020 %Y A031156 Cf. A031142, A031155. %K A031156 nonn,base %O A031156 1,2 %A A031156 _N. J. A. Sloane_