A209641 A014486-codes for rooted plane trees where non-leaf branches can occur only as the leftmost branch of any level, but nowhere else. Sorted into ascending order.

0, 2, 10, 12, 42, 50, 52, 56, 170, 202, 210, 212, 226, 228, 232, 240, 682, 810, 842, 850, 852, 906, 914, 916, 930, 932, 936, 962, 964, 968, 976, 992, 2730, 3242, 3370, 3402, 3410, 3412, 3626, 3658, 3666, 3668, 3722, 3730, 3732, 3746, 3748, 3752, 3850, 3858, 3860, 3874, 3876, 3880, 3906, 3908, 3912, 3920, 3970, 3972

Offset

0,2

Links

Antti Karttunen, Table of n, a(n) for n = 0..32767

Prog

(Scheme): (define (member_of_A209641? n) (let loop ((n n) (lev 0)) (cond ((zero? n) (zero? lev)) ((< lev 0) #f) ((even? n) (loop (/ n 2) (+ lev 1))) ((and (odd? (/ (-1+ n) 2)) (even? (/ (-1+ (/ (-1+ n) 2)) 2)) (not (zero? (/ (-1+ (/ (-1+ n) 2)) 2)))) #f) (else (loop (/ (- n 1) 2) (- lev 1))))))
(define A209641 (MATCHING-POS 0 0 member_of_A209641?)) ;; MATCHING-POS in AK's Scheme-SeqFun-Transform package.

Crossrefs

A209640(a(n)) = n for all n. a(n) = A014486(A209643(n)). Sequence A209642 sorted into ascending order with permutation A209862, i.e. a(n) = A209642(A209862(n)).

Sequence in context: A216649 A071162 A075165 * A209642 A061855 A358524

Adjacent sequences: A209638 A209639 A209640 * A209642 A209643 A209644

Keyword

nonn

Author

Antti Karttunen, Mar 24 2012

Status

approved