cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

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.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Dec 03 2012

Keywords

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).

Crossrefs

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

Programs

Formula

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

A230408 Partial sums of absolute values of A230407.

Original entry on oeis.org

0, 1, 2, 5, 10, 11, 14, 15, 18, 23, 24, 31, 32, 37, 38, 43, 48, 53, 58, 69, 70, 73, 84, 85, 88, 91, 92, 95, 100, 101, 108, 109, 114, 115, 120, 125, 130, 135, 146, 147, 150, 171, 172, 175, 178, 187, 188, 189, 194, 195, 200, 205, 210, 215, 226, 227, 230, 251, 252
Offset: 0

Views

Author

Antti Karttunen, Nov 10 2013

Keywords

Comments

The term a(n) tells how many nodes there are in total in all side-trees ("tendrils") encountered (see A230430) after we have climbed n steps up along the infinite trunk of the factorial beanstalk, A219666.
This sequence relates to the factorial base representation (A007623) in the same way as A218785 relates to the binary system.

Crossrefs

Formula

a(0) = 0, a(n) = a(n-1) + |A230407(n)| [Where | | indicates the absolute value].

A255333 Partial sums of A255330.

Original entry on oeis.org

1, 3, 3, 7, 8, 8, 15, 15, 18, 19, 19, 24, 26, 32, 32, 38, 38, 41, 42, 42, 47, 49, 61, 61, 63, 68, 68, 72, 74, 80, 80, 86, 86, 89, 90, 90, 95, 97, 109, 109, 111, 118, 119, 131, 135, 135, 137, 142, 142, 146, 148, 160, 160, 162, 167, 167, 171, 173, 179, 179, 185, 185, 188, 189, 189, 194
Offset: 0

Views

Author

Antti Karttunen, Feb 21 2015

Keywords

Crossrefs

Analogous sequences: A218785, A230408.

Formula

a(0) = 1; for n >= 1: a(n) = a(n-1) + A255330(n).
Other identities:
a(A255061(n)-1) = A000225(n) - A255062(n) for all n >= 2.
Equally: a(A255061(n)-1) + A255062(n) + 1 = A000079(n) = 2^n for all n >= 2.
Showing 1-3 of 3 results.