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 A257456 #4 Apr 24 2015 09:45:06 %S A257456 1,2,3,4,5,6,7,8,9,10,11,13,12,16,15,18,14,20,17,24,23,22,19,28,21,26, %T A257456 25,33,27,40,29,31,35,36,30,42,32,44,37,38,34,50,39,46,45,48,41,52,43, %U A257456 54,47,57,49,61,51,64,55,59,53,68,56,66,58,70,60,72,62 %N A257456 Smallest m, such that A257340(m) = n. %C A257456 A257340(a(n)) = n. %H A257456 Reinhard Zumkeller, <a href="/A257456/b257456.txt">Table of n, a(n) for n = 1..10000</a> %o A257456 (Haskell) %o A257456 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A257456 a257456 = (+ 1) . fromJust . (`elemIndex` a257340_list) %Y A257456 Cf. A257340. %K A257456 nonn %O A257456 1,2 %A A257456 _Reinhard Zumkeller_, Apr 24 2015