A262889 - OEIS

%I #8 Oct 04 2015 13:10:05

%S 0,0,0,0,0,0,0,0,0,0,0,1,0,2,0,0,0,3,0,1,13,0,0,0,1,1,2,2,0,0,0,0,0,0,

%T 2,3,0,0,5,0,4,0,1,7,0,0,7,0,0,0,0,0,6,0,0,0,0,1,0,0,0,2,0,0,1,0,0,1,

%U 0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,5,1,0,1,0,0,0,1,0,0,0,1,0,0,3,0,22,1,0,1,2,0,6,0,0,0,0,0,0

%N a(n) = total number of nodes in the finite subtrees branching "right" (to the "larger side") from node n in the infinite trunk (A259934) of the tree generated by edge-relation A049820(child) = parent.

%H Antti Karttunen, <a href="/A262889/b262889.txt">Table of n, a(n) for n = 0..8107</a>

%F a(n) = sum_{k = A259934(n+1) .. A262686(A259934(n))} [A049820(k) = A259934(n)] * A262697(k).

%F (Here [ ] stands for Iverson bracket, giving as its result 1 only when A049820(k) = A259934(n), and 0 otherwise).

%F Other identities. For all n >= 0:

%F A262890(n) = A262888(n) + a(n).

%o (Scheme)

%o (define (A262889 n) (let ((t (A259934 n)) (u (A259934 (+ 1 n)))) (let loop ((s 0) (k (A262686 t))) (cond ((<= k u) s) ((= t (A049820 k)) (loop (+ s (A262697 k)) (- k 1))) (else (loop s (- k 1)))))))

%Y Cf. A000005, A049820, A082284, A259934, A262686, A262697, A262888, A262890, A262894.

%Y Cf. also A255329.

%K nonn

%O 0,14

%A _Antti Karttunen_, Oct 04 2015