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 A179977 #5 Mar 20 2022 21:42:37 %S A179977 1,2,3,4,5,6,7,8,9,17,16,15,14,13,12,11,10,25,26,18,19,20,21,22,23,24, %T A179977 27,28,29,37,36,35,34,33,32,31,30,45,46,38,39,40,41,42,43,44,47,48,49, %U A179977 57,56,55,54,53,52,51,50,65,66,58,59,60,61,62,63,64,67,68,69,77,76,75 %N A179977 Inverse permutation to A108971. %C A179977 a(A108971(n)) = A108971(a(n)) = n; %C A179977 a(A179978(n)) = A179978(a(n)) = A108971(n). %K A179977 nonn %O A179977 1,2 %A A179977 _Reinhard Zumkeller_, Aug 04 2010