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 A099135 #12 Jun 17 2017 03:04:37 %S A099135 1,3,6,8,10,13,12,4,5,11,14,2,7,9,15,16,17,18,19,20,21,22,23,24,25,26, %T A099135 27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49, %U A099135 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72 %N A099135 a(n) = smallest number m, not occurring earlier, such that a(k)+m is a square for some k<n; a(1) = 1. %C A099135 Permutation of the natural numbers with inverse A099136; %C A099135 a(n) <> n iff 1 < n <= 14. %H A099135 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %H A099135 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1). %o A099135 (PARI) a(n)=if(n>14,n,[1, 3, 6, 8, 10, 13, 12, 4, 5, 11, 14, 2, 7, 9][n]) \\ _Charles R Greathouse IV_, Sep 02 2011 %Y A099135 Cf. A048761, A068527. %K A099135 nonn,easy %O A099135 1,2 %A A099135 _Reinhard Zumkeller_, Sep 29 2004