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 A376674 #9 Oct 03 2024 11:02:33 %S A376674 2,1,6,5,4,3,10,9,8,7,16,15,14,13,12,11,24,23,22,21,20,19,18,17,28,27, %T A376674 26,25,40,39,38,37,36,35,34,33,32,31,30,29,48,47,46,45,44,43,42,41,56, %U A376674 55,54,53,52,51,50,49,68,67,66,65,64,63,62,61,60,59,58 %N A376674 a(n) is the unique number k different from n such that the words A376637(n) and A376637(k) have the same run lengths transform. %C A376674 Also, replacing 1's by 2's and 2's by 1's in A376637(n) yields A376637(a(n)). %C A376674 This sequence is a self-inverse permutation of the positive integers without fixed points. %H A376674 Rémy Sigrist, <a href="/A376674/b376674.txt">Table of n, a(n) for n = 1..10048</a> %H A376674 Rémy Sigrist, <a href="/A376674/a376674.gp.txt">PARI program</a> %H A376674 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A376674 A351653(A376637(a(n))) = A351653(A376637(n)). %e A376674 The first terms, alongside the corresponding terms from A376637 and their run lengths transform, are: %e A376674 n a(n) A376637(n) A376637(a(n)) RL %e A376674 -- ---- ---------- ------------- --- %e A376674 1 2 1 2 1 %e A376674 2 1 2 1 1 %e A376674 3 6 11 22 2 %e A376674 4 5 12 21 11 %e A376674 5 4 21 12 11 %e A376674 6 3 22 11 2 %e A376674 7 10 112 221 21 %e A376674 8 9 122 211 12 %e A376674 9 8 211 122 12 %e A376674 10 7 221 112 21 %e A376674 11 16 1121 2212 211 %e A376674 12 15 1122 2211 22 %e A376674 13 14 1211 2122 112 %e A376674 14 13 2122 1211 112 %e A376674 15 12 2211 1122 22 %e A376674 16 11 2212 1121 211 %o A376674 (PARI) \\ See Links section. %Y A376674 Cf. A351653, A376637. %K A376674 nonn,base %O A376674 1,1 %A A376674 _Rémy Sigrist_, Oct 01 2024