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 A375472 #13 Aug 17 2024 22:51:34 %S A375472 1,2,8,14,24,26,42,45,50,53,70,74,96,76,124,98,116,121,143,141,179, %T A375472 150,187,181,192,215,209,233,220,257,245,264,243,278,260,310,297,303, %U A375472 315,339,329,387,341,357,354,366,403,420,350,400,411,415,474,455,466,442 %N A375472 Least k such that the ternary representation of 2^k has exactly 2*n 1's, or -1 if no such k exists. %F A375472 Conjecture: a(n) ~ 6*log_2(3)*n = 6*A020857*n. %e A375472 For n = 3, the smallest power of 2 with exactly 2*3 = 6 1's in its ternary representation is 2^14 = 211110211_3, so a(3) = 14. %o A375472 (PARI) a(n) = my(k=1); while (#select(x->(x==1), digits(2^k, 3)) != 2*n, k++); k; \\ _Michel Marcus_, Aug 17 2024 %Y A375472 Cf. A020857, A060035, A104321, A365214. %K A375472 nonn,base %O A375472 0,2 %A A375472 _Pontus von Brömssen_, Aug 17 2024