A218618 Absolute value of a(n) tells the size of the n-th side-tree ("tendril", A213730(n)) in the binary beanstalk; the sign tells on which side of the infinite trunk (A179016) it is.

0, 1, -1, 1, -1, 3, 1, -1, 3, 5, -1, 1, -1, 3, 5, -1, -7, 1, 1, 3, 1, -1, 3, 5, -1, -7, 1, 1, 3, -7, 1, 1, -5, 1, -5, -3, -1, 1, -1, 3, 5, -1, -7, 1, 1, 3, -7, 1, 1, -5, 1, -5, -3, -1, -7, 1, 1, -5, 1, 11, 1, 1, 13, 1, -5, -1, 3, 1, -1, 3, 5, -1, -7, 1, 1, 3

Offset

0,6

Comments

Positive and negative terms correspond to the tendrils that sprout respectively at the left and right sides of the infinite trunk, when the beanstalk is drawn with the lesser numbers branching to the left. The absolute values give the sizes of those tendrils, with all nodes included: The leaves, the internal vertices as well as the root itself: A213730(n).

Links

Antti Karttunen, Table of n, a(n) for n = 0..8727

Formula

a(n) = -1^A213730(n) * A213727(A213730(n)).

Prog

(Scheme): (define (A218618 n) (* (expt -1 (A213730 n)) (A213727 (A213730 n))))

Crossrefs

Partial sums: A218785, A218789. Cf. also A218786, A218613.

Sequence in context: A319182 A247282 A246685 * A271451 A131248 A116445

Adjacent sequences: A218615 A218616 A218617 * A218619 A218620 A218621

Keyword

sign

Author

Antti Karttunen, Dec 03 2012

Status

approved