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 A306993 #13 Mar 21 2019 13:26:22 %S A306993 2,1,3,11,7,25,5,23,15,17,4,13,12,43,9,47,10,31,29,37,34,26,8,39,6,22, %T A306993 30,81,19,27,18,95,63,21,61,67,20,57,24,70,56,51,14,55,49,54,16,53,45, %U A306993 58,42,65,48,46,44,41,38,50,62,149,35,59,33,191,52,127,36 %N A306993 Lexicographically earliest sequence of distinct positive terms such that for any n > 0, n * a(n) is digitally balanced. %C A306993 Digitally balanced numbers correspond to A031443. %C A306993 This sequence has similarities with A300868. %C A306993 This sequence is a self-inverse permutation of the natural numbers. %H A306993 Rémy Sigrist, <a href="/A306993/b306993.txt">Table of n, a(n) for n = 1..10000</a> %H A306993 Rémy Sigrist, <a href="/A306993/a306993.gp.txt">PARI program for A306993</a> %H A306993 Rémy Sigrist, <a href="/A306993/a306993.png">Colored scatterplot of the first 10000 terms</a> (where the color is function of A000120(n*a(n))) %H A306993 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %e A306993 The first terms, alongside the binary representation of n * a(n), are: %e A306993 n a(n) bin(n * a(n)) %e A306993 -- ---- -------------- %e A306993 1 2 10 %e A306993 2 1 10 %e A306993 3 3 1001 %e A306993 4 11 101100 %e A306993 5 7 100011 %e A306993 6 25 10010110 %e A306993 7 5 100011 %e A306993 8 23 10111000 %e A306993 9 15 10000111 %e A306993 10 17 10101010 %e A306993 11 4 101100 %e A306993 12 13 10011100 %e A306993 13 12 10011100 %e A306993 14 43 1001011010 %e A306993 15 9 10000111 %e A306993 16 47 1011110000 %o A306993 (PARI) See Links section. %Y A306993 Cf. A000120, A031443, A300868. %K A306993 nonn,look,base %O A306993 1,1 %A A306993 _Rémy Sigrist_, Mar 18 2019