A218791 a(n) = binary code (shown here in decimal) of the position of the predecessor of the natural number pair (2n,2n+1) in the compact beanstalk-tree A218780.

1, 2, 6, 10, 26, 58, 42, 74, 202, 458, 330, 842, 586, 1354, 1610, 2634, 6730, 14922, 10826, 27210, 19018, 43594, 51786, 117322, 84554, 182858, 215626, 313930, 477770, 838218, 576074, 1100362, 3197514, 7391818, 5294666, 13683274, 9488970, 22071882, 26266186

Offset

1,2

Links

A. Karttunen, Table of n, a(n) for n = 1..1024

Formula

a(n) = A218615(A005187(n)).

Prog

(Scheme) ;; With memoization-macro definec:
(definec (A218791 n) (cond ((< n 2) n) ((A011371 (* 2 n)) => (lambda (bp) (if (odd? bp) (A004754 (A218791 (/ (-1+ bp) 2))) (A004755 (A218791 (/ bp 2))))))))

Crossrefs

Subset of A218615, i.e., a(n) = A218615(A005187(n)).

Also, a(n) = A054429(A218790(n)). (Note also how the first five or so terms are twice the terms in the beginning of A218790, shifted by one term.)

Used to construct A218780, A218781. Cf. also A218787, A218788.

Sequence in context: A333997 A162581 A061547 * A320429 A319014 A190034

Adjacent sequences: A218788 A218789 A218790 * A218792 A218793 A218794

Keyword

nonn,base

Author

Antti Karttunen, Nov 16 2012

Status

approved