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 A338834 #12 Nov 14 2020 01:50:28 %S A338834 0,1,2,4,3,5,6,12,8,18,14,20,7,13,10,19,16,22,9,15,11,21,17,23,24,48, %T A338834 30,72,54,96,26,50,49,78,74,102,36,73,60,98,97,108,56,84,80,104,103, %U A338834 114,25,32,31,55,52,79,28,51,42,76,75,100,38,66,62,99,90,110 %N A338834 a(n) is the greatest number not yet in the sequence with the same number of digits and the same sum of digits as n in factorial base. %C A338834 This sequence is a self-inverse permutation of the nonnegative integers. %H A338834 Rémy Sigrist, <a href="/A338834/b338834.txt">Table of n, a(n) for n = 0..5039</a> %H A338834 Rémy Sigrist, <a href="/A338834/a338834.png">Colored scatterplot of the first 7! terms</a> (where the color is function of A034968(n)) %H A338834 Rémy Sigrist, <a href="/A338834/a338834.gp.txt">PARI program for A338834</a> %H A338834 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A338834 A084558(a(n)) = A084558(n). %F A338834 A034968(a(n)) = A034968(n). %e A338834 For n = 26: %e A338834 - the numbers with 4 digits and sum of digits 2 in factorial base are: 25 ("1001"), 26 ("1010"), 30 ("1100") and 48 ("2000"), %e A338834 - so a(25) = 40, %e A338834 a(26) = 30, %e A338834 a(30) = 26, %e A338834 a(40) = 25. %o A338834 (PARI) See Links section. %Y A338834 Cf. A034968, A084558, A337598, A338829 (decimal analog), A338835 (primorial base analog). %K A338834 nonn,base %O A338834 0,3 %A A338834 _Rémy Sigrist_, Nov 11 2020