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 A300855 #10 Mar 14 2018 21:01:14 %S A300855 0,1,2,3,4,17,16,15,14,5,18,11,12,13,6,19,10,9,8,7,20,21,22,23,24,97, %T A300855 96,95,94,85,48,49,50,51,84,47,54,53,52,83,46,55,56,57,82,37,36,35,34, %U A300855 25,98,91,92,93,86,43,66,65,64,79,44,61,62,63,80,45,60,59,58,81 %N A300855 Inverse of Knuth's base-5 based twisted permutation A220952 of the nonnegative integers. %H A300855 Alois P. Heinz, <a href="/A300855/b300855.txt">Table of n, a(n) for n = 0..15624</a> %F A300855 A220952(9) = 5, therefore a(5) = 9. %o A300855 (PARI) concat(0,Vec(vecsort(A220952,,1))) \\ where A220952 is a vector of some N initial terms of that sequence without the leading a(0) = 0 (use ...[^1] to exclude the first element if needed) and such that these N values contain exactly all integers from 1 to N, e.g., N = 120. %Y A300855 See A220952 for the inverse permutation, A300857 and its inverse A300856 for the base-7 variant. %K A300855 nonn,look %O A300855 0,3 %A A300855 _M. F. Hasler_, Mar 13 2018