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 A292603 #17 Dec 01 2017 18:51:16 %S A292603 1,2,3,0,1,2,1,0,3,2,3,0,1,2,3,0,3,2,1,0,3,2,1,0,1,2,3,0,1,2,1,0,1,2, %T A292603 1,0,3,2,3,0,1,2,1,0,3,2,3,0,1,2,3,0,1,2,1,0,3,2,3,0,1,2,3,0,1,2,3,0, %U A292603 1,2,3,0,3,2,1,0,3,2,1,0,3,2,3,0,1,2,3,0,3,2,1,0,3,2,1,0,1,2,3,0,1,2,1,0,3,2,3,0,1,2,3,0,3,2,1,0,3,2,1,0,1 %N A292603 Doudna-tree reduced modulo 4: a(n) = A005940(1+n) mod 4. %H A292603 Antti Karttunen, <a href="/A292603/b292603.txt">Table of n, a(n) for n = 0..16383</a> %H A292603 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a> %F A292603 a(n) = A010873(A005940(1+n)). %F A292603 a(n) + 4*A292602(n) = A005940(1+n). %F A292603 a(2n+1) = 2*a(n) mod 4. %F A292603 a(A004767(n)) = 0. %F A292603 a(A016813(n)) = 2. %F A292603 a(2*A156552(A246261(n))) = 1. %F A292603 a(2*A156552(A246263(n))) = 3. %F A292603 a(n * 2^(1+A246271(A005940(1+n)))) = 1. %e A292603 The first six levels of the binary tree (compare also to the illustrations given at A005940 and A292602): %e A292603 1 %e A292603 | %e A292603 2 %e A292603 ............../ \.............. %e A292603 3 0 %e A292603 ....../ \...... ....../ \...... %e A292603 1 2 1 0 %e A292603 / \ / \ / \ / \ %e A292603 / \ / \ / \ / \ %e A292603 3 2 3 0 1 2 3 0 %e A292603 / \ / \ / \ / \ / \ / \ / \ / \ %e A292603 3 2 1 0 3 2 1 0 1 2 3 0 1 2 1 0 %o A292603 (Scheme) (define (A292603 n) (modulo (A005940 (+ 1 n)) 4)) %Y A292603 Cf. A003961, A005940, A292602. %Y A292603 Cf. A004767 (gives the positions of 0's), A016813 (of 2's). %Y A292603 Cf. also A246261, A246263, A246271, A292271, A292274, A292375, A292377, A292381, A292383, A292384, A292583. %K A292603 nonn %O A292603 0,2 %A A292603 _Antti Karttunen_, Dec 01 2017