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 A338245 #20 Nov 30 2020 10:57:17 %S A338245 0,1,3,4,2,9,10,8,12,13,11,6,7,5,27,28,26,30,31,29,24,25,23,36,37,35, %T A338245 39,40,38,33,34,32,18,19,17,21,22,20,15,16,14,81,82,80,84,85,83,78,79, %U A338245 77,90,91,89,93,94,92,87,88,86,72,73,71,75,76,74,69,70,68 %N A338245 Nonnegative values in A117966, in order of appearance. %C A338245 This sequence is a permutation of the nonnegative integers with inverse A338247 (the offset has been set to 0 so as to get a permutation). %C A338245 There are only two fixed points: a(0) = 0 and a(1) = 1. %H A338245 Rémy Sigrist, <a href="/A338245/b338245.txt">Table of n, a(n) for n = 0..9841</a> %H A338245 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A338245 a(0) = 0. %F A338245 a(n) = A117966(A132141(n)) for any n > 0. %e A338245 A117966 = 0, 1, -1, 3, 4, 2, -3, -2, -4, 9, 10, 8, 12, 13, 11, 6, 7, 5, ... %e A338245 We keep: 0, 1, 3, 4, 2, 9, 10, 8, 12, 13, 11, 6, 7, 5, ... %o A338245 (PARI) A117966(n) = subst(Pol(apply(x->if(x == 2, -1, x), digits(n, 3)), 'x), 'x, 3) %o A338245 print (select(v -> v>=0, apply(A117966, [0..107]))) %Y A338245 See A338248 for a similar sequence. %Y A338245 Cf. A117966, A132141, A338246, A338247. %K A338245 nonn,base %O A338245 0,3 %A A338245 _Rémy Sigrist_, Oct 18 2020