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 A263110 #13 Feb 16 2025 08:33:27 %S A263110 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,3,3,3, %T A263110 3,3,3,3,3,3,3,3,3,3,3,2,1,4,4,4,4,4,4,4,4,4,4,4,4,4,3,2,1,5,5,5,5,5, %U A263110 5,5,5,5,5,5,5,4,3,2,1,6,6,6,6,6,6,6 %N A263110 n is the a(n)-th positive integer having its digitsum in base-16 representation. %C A263110 Ordinal transform of A053836. - _Alois P. Heinz_, Dec 23 2018 %H A263110 Reinhard Zumkeller, <a href="/A263110/b263110.txt">Table of n, a(n) for n = 1..10000</a> %H A263110 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Hexadecimal.html">Hexadecimal</a> %H A263110 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DigitSum.html">Digit Sum</a> %H A263110 Wikipedia, <a href="http://en.wikipedia.org/wiki/Hexadecimal">Hexadecimal</a> %H A263110 Wikipedia, <a href="http://en.wikipedia.org/wiki/Digit_sum">Digit sum</a> %o A263110 (Haskell) %o A263110 import Data.IntMap (empty, findWithDefault, insert) %o A263110 a263110 n = a263110_list !! (n-1) %o A263110 a263110_list = f 1 empty where %o A263110 f x m = y : f (x + 1) (insert q (y + 1) m) where %o A263110 y = findWithDefault 1 q m; q = a053836 x %Y A263110 Cf. A053836, A254524, A263017, A263109. %K A263110 nonn,base %O A263110 1,16 %A A263110 _Reinhard Zumkeller_, Oct 09 2015