A191379 Expansion of product(n>=0, 1+2*x^(3^n)+x^(2*3^n)+2*x^(3*3^n)+x^(4*3^n) ).

1, 2, 1, 4, 5, 2, 5, 4, 1, 6, 9, 4, 13, 14, 5, 12, 9, 2, 9, 12, 5, 14, 13, 4, 9, 6, 1, 8, 13, 6, 21, 24, 9, 22, 17, 4, 21, 30, 13, 40, 41, 14, 33, 24, 5, 22, 29, 12, 33, 30, 9, 20, 13, 2, 13, 20, 9, 30, 33, 12, 29, 22, 5, 24, 33, 14, 41, 40, 13, 30, 21, 4, 17, 22, 9, 24, 21, 6, 13, 8, 1, 10

Offset

0,2

Comments

This is an analog of the classical Stern sequence (A002487) with generating function product(n>=0, 1+x^(2^n)+x^(2*2^n) ).

The author of the linked paper proves that the sequence {a(n)/a(n+1)} enumerates the set of positive rational numbers with either an even numerator or an even denominator.

Links

Table of n, a(n) for n=0..81.

Song Heng Chan, Analogs of the Stern Sequence,INTEGERS 11(2011) #A26 (10 pages).

Crossrefs

Cf. A002487.

Sequence in context: A091564 A321301 A359058 * A038574 A212713 A072014

Adjacent sequences: A191376 A191377 A191378 * A191380 A191381 A191382

Keyword

nonn

Author

John W. Layman, Jun 01 2011

Status

approved