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 A099136 #14 Mar 03 2023 16:42:35
%S A099136 1,12,2,8,9,3,13,4,14,5,10,7,6,11,15,16,17,18,19,20,21,22,23,24,25,26,
%T A099136 27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,
%U A099136 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72
%N A099136 Inverse integer permutation to A099135.
%C A099136 a(n) <> n iff 1 < n <= 14.
%H A099136 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%H A099136 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%t A099136 LinearRecurrence[{2,-1},{1,12,2,8,9,3,13,4,14,5,10,7,6,11,15,16},80] (* _Harvey P. Dale_, Mar 03 2023 *)
%o A099136 (PARI) a(n)=if(n>14,n,[1, 12, 2, 8, 9, 3, 13, 4, 14, 5, 10, 7, 6, 11][n]) \\ _Charles R Greathouse IV_, Sep 02 2011
%K A099136 nonn,easy
%O A099136 1,2
%A A099136 _Reinhard Zumkeller_, Sep 29 2004