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 A169840 #8 Apr 27 2023 15:01:53 %S A169840 2,4,1,9,3,13,7,5,8,19,6,27,12,10,16,32,11,36,17,14,18,42,15,23,26,21, %T A169840 25,56,22,60,30,20,31,24,29,66,35,28,39,73,34,80,40,38,41,88,44,49,45, %U A169840 33,46,99,47,52,48,37,55,106,51,114,59,50,63,53,58,127,64,43,54,133,62,137,65 %N A169840 a(n) = position of n in A169839. %C A169840 A generalization of A064421. %Y A169840 Cf. A064421, A169839. %K A169840 nonn %O A169840 2,1 %A A169840 _T. D. Noe_ and _N. J. A. Sloane_, Jun 02 2010