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 A332990 #10 Mar 05 2020 18:49:24 %S A332990 1,2,3,4,5,6,9,7,8,10,17,11,33,18,12,13,65,14,129,19,20,34,257,21,15, %T A332990 66,16,35,513,22,1025,23,36,130,24,25,2049,258,67,37,4097,38,8193,68, %U A332990 26,514,16385,39,27,28,131,132,32769,29,40,69,259,1026,65537,41 %N A332990 Inverse of permutation in A332977. %C A332990 Permutation of the natural numbers A000027 with fixed points 1, 2, 3, 4, 5, 6, 10, ... and inverse permutation A332977 (with offset 1). %H A332990 Alois P. Heinz, <a href="/A332990/b332990.txt">Table of n, a(n) for n = 1..20000</a> %H A332990 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A332990 a(p) = 1 + 2^(pi(p)-1) = A094373(A000720(p)) for prime p. %Y A332990 Cf. A000027, A000040, A000720 (pi), A094373, A332977. %K A332990 nonn %O A332990 1,2 %A A332990 _Alois P. Heinz_, Mar 05 2020