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 A374611 #10 Jul 17 2024 15:56:31 %S A374611 1,3,2,7,9,6,4,13,5,19,21,14,8,12,18,27,29,15,10,37,11,39,43,26,49,24, %T A374611 16,28,17,38,53,57,42,61,36,35,20,30,22,63,71,33,23,79,45,81,87,54,25, %U A374611 89,58,56,31,48,91,52,32,51,101,74,34,107,40,111,72,78 %N A374611 If n = A066207(i) * A066208(j) for some i, j > 0 then a(n) = A066207(j) * A066208(i). %C A374611 This sequence is a self-inverse permutation of the positive integers with infinitely many fixed points. %H A374611 Rémy Sigrist, <a href="/A374611/b374611.txt">Table of n, a(n) for n = 1..10000</a> %H A374611 Rémy Sigrist, <a href="/A374611/a374611.gp.txt">PARI program</a> %H A374611 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A374611 a(A360646(n, k)) = A360646(k, n). %F A374611 a(n) = n iff n = A066207(k) * A066208(k) for some k > 0. %e A374611 For n = 42: 42 = 21 * 2 = A066207(7) * A066208(2), so a(42) = A066207(2) * A066208(7) = 3 * 11 = 33. %o A374611 (PARI) \\ See Links section. %Y A374611 See A374600 for a similar sequence. %Y A374611 Cf. A066207, A066208, A247503, A248101, A360646. %K A374611 nonn %O A374611 1,2 %A A374611 _Rémy Sigrist_, Jul 14 2024