login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A117592 a(n)=a(3n)=a(3n+1)=a(3n+2)/2 with a(0)=1. 9
1, 1, 2, 1, 1, 2, 2, 2, 4, 1, 1, 2, 1, 1, 2, 2, 2, 4, 2, 2, 4, 2, 2, 4, 4, 4, 8, 1, 1, 2, 1, 1, 2, 2, 2, 4, 1, 1, 2, 1, 1, 2, 2, 2, 4, 2, 2, 4, 2, 2, 4, 4, 4, 8, 2, 2, 4, 2, 2, 4, 4, 4, 8, 2, 2, 4, 2, 2, 4, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Row sums of number triangle A117944.

Product of the nonzero digits of (n written in base 3). - Ilya Gutkovskiy, Nov 15 2020

a(n) = 1, 2, 4, 8, 16, 32, 64 iff n is respectively in A005836, A023699, A023700, A023701, A023702, A023703, A023704. - Bernard Schott, Dec 04 2020

LINKS

Felix Fröhlich, Table of n, a(n) for n = 0..10000 (first 2001 terms from Vincenzo Librandi)

FORMULA

a(n) = a(3n)/a(0) = a(3n+1)/a(1) = a(3n+2)/a(2).

a(n) = abs(A117942(n)).

G.f. A(x) satisfies: A(x) = (1 + x + 2*x^2) * A(x^3). - Ilya Gutkovskiy, Nov 15 2020

a(n) = 2^A081603(n). - Kevin Ryde, Nov 15 2020

MATHEMATICA

Nest[ Join[#, #, 2#] &, {1}, 5] (* Robert G. Wilson v, Jul 27 2014 *)

PROG

(PARI) a(n) = 1 << hammingweight(digits(n, 3)>>1); \\ Kevin Ryde, Nov 15 2020

CROSSREFS

See A338882 for similar sequences.

Cf. A081603 (log2), A117942 (signed), A117944.

Cf. A005836, A023699, A023700, A023701, A023702, A023703, A023704.

Sequence in context: A133098 A145788 A323861 * A117942 A290092 A066877

Adjacent sequences:  A117589 A117590 A117591 * A117593 A117594 A117595

KEYWORD

nonn,base

AUTHOR

Paul Barry, Apr 05 2006

EXTENSIONS

Added a(0) = 1 in the Name by Bernard Schott, Dec 04 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 17 02:26 EDT 2021. Contains 343059 sequences. (Running on oeis4.)