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 A365214 #12 Aug 17 2024 16:01:18 %S A365214 0,1,4,3,7,5,-1,9,10,12,13,-1,11,14,15,24,19,25,22,21,-1,23 %N A365214 Least k such that the binary representation of 3^k has exactly n 1's, or -1 if no such k exists. %C A365214 Least k such that A011754(k) = n, or -1 if no such k exists. %C A365214 The first 22 terms are from Dimitrov and Howe (2021). After a(22), the sequence continues (with the -1's conjectural but very likely correct) -1, 26, 28, 31, 36, 40, 34, 27, -1, 35, 49, 33, 53, 38, -1, 42, 41, 57, 48, 52, -1, -1, 46, 51, 67, 59, 62, -1, ... . %H A365214 Vassil S. Dimitrov and Everett W. Howe, <a href="https://arxiv.org/abs/2105.06440">Powers of 3 with few nonzero bits and a conjecture of Erdős</a>, arXiv:2105.06440 [math.NT], 2021. %Y A365214 Cf. A011754, A364650, A365215, A375472. %K A365214 sign,base,more %O A365214 1,3 %A A365214 _Pontus von Brömssen_, Aug 26 2023