A285726 - OEIS

%I #5 Apr 25 2017 11:47:50

%S 0,0,0,0,0,0,0,1,1,0,0,1,0,0,1,2,0,1,0,1,1,0,0,2,1,0,2,1,0,1,0,3,1,0,

%T 1,2,0,0,1,2,0,1,0,1,2,0,0,3,1,1,1,1,0,2,1,2,1,0,0,2,0,0,2,4,1,1,0,1,

%U 1,1,0,3,0,0,2,1,1,1,0,3,3,0,0,2,1,0,1,2,0,2,1,1,1,0,1,4,0,1,2,2,0,1,0,2,2,0,0,3,0,1,1,3,0,1,1,1,2,0,1,3

%N a(1) = a(2) = 0; for n > 2, a(n) = A252736(n) - (1-A000035(n)).

%C Consider the binary tree illustrated in A005940: If we start from any n, computing successive iterations of A252463 until 1 is reached (i.e., we are traversing level by level towards the root of the tree, starting from that vertex of the tree where n is located), then a(n) gives the number of even numbers > 2 encountered on the path after the initial n, that is, both the penultimate 2 and also the starting n (if it was even) are excluded from the count.

%H Antti Karttunen, <a href="/A285726/b285726.txt">Table of n, a(n) for n = 1..8192</a>

%F a(1) = a(2) = 0; for n > 2, a(n) = A252736(n) - (1-A000035(n)).

%o (Scheme) (define (A285726 n) (if (<= n 2) 0 (- (A252736 n) (- 1 (A000035 n)))))

%Y Cf. A000035, A005940, A252463, A252736, A285725.

%K nonn

%O 1,16

%A _Antti Karttunen_, Apr 25 2017