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 A112978 #6 Mar 30 2012 18:50:53 %S A112978 1,2,3,5,12,4,17,6,7,8,27,9,33,10,11,13,43,14,49,15,16,18,59,19,20,21, %T A112978 22,23,74,24,80,25,26,28,29,30,94,31,32,34,106,35,112,36,37,38,122,39, %U A112978 40,41,42,44,138,45,46,47,48,50,154,51,159,52,53,54,55,56,174,57,58,60 %N A112978 Inverse of A112975. %C A112978 A112979 = a(a(n)); %C A112978 a(n) = A112975(A112979(n)) = A112979(A112975(n)). %H A112978 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %Y A112978 Cf. A112990. %K A112978 nonn %O A112978 1,2 %A A112978 _Reinhard Zumkeller_, Oct 08 2005