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 A065257 #8 May 01 2014 02:49:08 %S A065257 1,3,5,2,4,11,13,15,12,14,21,23,25,22,24,6,8,10,7,9,16,18,20,17,19,51, %T A065257 53,55,52,54,61,63,65,62,64,71,73,75,72,74,56,58,60,57,59,66,68,70,67, %U A065257 69,101,103,105,102,104,111,113,115,112,114,121,123,125,122,124,106 %N A065257 Quintal Queens permutation of N: double (mod 5) each digit (0->0, 1->2, 2->4, 3->1, 4->3) of the base-5 representation of n-1, add one. %C A065257 See comment at A065256. %H A065257 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %p A065257 [seq(QuintalQueens1(j),j=1..125)]; QuintalQueens0 := n -> DoubleDigits(n,5); QuintalQueens1 := n -> 1+QuintalQueens0(n-1); %p A065257 DoubleDigits := proc(n,b) local i; add((b^i)*((2*floor(n/(b^i))) mod b),i=0..floor(evalf(log[b](n+1)))+1); end; %Y A065257 Inverse permutation: A065258. A065257[n] = A004515[n-1]+1. Cf. also A065186, A065188. %K A065257 nonn,base %O A065257 1,2 %A A065257 _Antti Karttunen_, Oct 26 2001