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 A246680 #7 Sep 11 2014 18:58:01 %S A246680 1,2,4,3,7,12,13,5,10,17,22,24,16,62,40,6,37,27,31,38,19,87,67,60,25, %T A246680 32,49,171,52,312,121,8,28,122,112,45,34,137,94,71,82,42,58,269,43, %U A246680 437,202,84,73,47,76,59,187,162,148,665,46,192,157,1200,55,1562,364,9,97,57,85,423,115,612,337,93,61,72 %N A246680 Permutation of natural numbers, even bisection of A246676 halved: a(n) = A246676(2*n)/2. %C A246680 Equally: even bisection of A246678 halved. %H A246680 Antti Karttunen, <a href="/A246680/b246680.txt">Table of n, a(n) for n = 1..8192</a> %H A246680 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A246680 a(n) = A246676(2*n)/2. %F A246680 a(n) = A246678(2*n)/2. %o A246680 (Scheme) (define (A246680 n) (/ (A246676 (* 2 n)) 2)) %Y A246680 Inverse: A246679. %Y A246680 Cf. A246676, A246678. %K A246680 nonn %O A246680 1,2 %A A246680 _Antti Karttunen_, Sep 02 2014