A081848 Number of numbers whose base-3/2 expansion (see A024629) has n digits.

3, 3, 3, 6, 9, 12, 18, 27, 42, 63, 93, 141, 210, 315, 474, 711, 1065, 1599, 2397, 3597, 5394, 8091, 12138, 18207, 27309, 40965, 61446, 92169, 138255, 207381, 311073, 466608, 699912, 1049868, 1574802, 2362203, 3543306, 5314959, 7972437, 11958657

Offset: 1

Author

N. J. A. Sloane, Apr 13 2003

Keywords

• easy
• nonn
• base

Comments

Run lengths in A246435. - Reinhard Zumkeller, Sep 05 2014

Examples

			a(1) = 3 because 0, 1 and 2 each have 1 digit.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
• B. Chen, R. Chen, J. Guo, S. Lee et al., On Base 3/2 and its sequences, arXiv:1808.04304 [math.NT], 2018.
• J. S. Tanton, A collection of research problems.

Crossrefs

Cf. A024629, A070885, A073941, A246435.

Programs

Haskell

a081848 n = a081848_list !! (n-1)
a081848_list = 3 : tail (zipWith (-) (tail a070885_list) a070885_list)
-- Reinhard Zumkeller, Sep 05 2014

Python

from itertools import islice
def A081848_gen(): # generator of terms
    yield (a:=3)
    while True:
        yield (b:=(a+1>>1)+(a&1))
        a += b
A081848_list = list(islice(A081848_gen(),70)) # Chai Wah Wu, Sep 20 2022

Formula

For n > 1, a(n) = A070885(n+1) - A070885(n). - Tom Edgar, Jun 25 2014

a(n) = 3*A073941(n). - Tom Edgar, Jul 21 2014

Extensions

More terms from David Wasserman, Jun 28 2004

Edited by Charles R Greathouse IV, Aug 02 2010