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 A355405 #10 Jul 04 2022 13:57:11 %S A355405 1,2,3,4,5,6,9,8,7,10,17,11,33,18,13,12,65,14,129,20,19,34,257,16,21, %T A355405 66,15,25,513,22,1025,24,35,130,37,23,2049,258,67,26,4097,38,8193,36, %U A355405 29,514,16385,27,41,42,131,68,32769,30,49,40,259,1026 %N A355405 Inverse permutation to A269838. %H A355405 Rémy Sigrist, <a href="/A355405/b355405.txt">Table of n, a(n) for n = 1..10000</a> %H A355405 Rémy Sigrist, <a href="/A355405/a355405.gp.txt">PARI program</a> %H A355405 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A355405 a(prime(n)) = 2^(n-1) + 1 (where prime(n) denotes the n-th prime number). %e A355405 A269838(38) = 42, so a(42) = 38. %o A355405 (PARI) See Links section. %Y A355405 Cf. A269838. %K A355405 nonn %O A355405 1,2 %A A355405 _Rémy Sigrist_, Jul 01 2022