A004647 Powers of 2 written in base 8.

1, 2, 4, 10, 20, 40, 100, 200, 400, 1000, 2000, 4000, 10000, 20000, 40000, 100000, 200000, 400000, 1000000, 2000000, 4000000, 10000000, 20000000, 40000000, 100000000, 200000000, 400000000, 1000000000

Offset

0,2

Comments

Or, numbers of form 10^n, 2*10^n, 4*10^n.

Or, numbers n such that the digits of n^3 are decreasing. - Dmitry Kamenetsky, Jun 15 2006

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Thomas Harriot, Manuscript 6782, p. 1, c. 1599.

D. Panario, M. Sahin, and Q. Wang, A family of Fibonacci-like conditional sequences, INTEGERS, Vol. 13, 2013, #A78.

Index entries for linear recurrences with constant coefficients, signature (0,0,10).

Formula

a(0)=1, a(1)=2, a(2)=4, a(n)=10*a(n-3). - Harvey P. Dale, Aug 16 2012

G.f.: (1 + 2*x + 4*x^2)/(1 - 10*x^3 ). - R. J. Mathar, Mar 13 2015

Mathematica

Table[FromDigits[IntegerDigits[2^n, 8]], {n, 0, 30}] (* or *) LinearRecurrence[ {0, 0, 10}, {1, 2, 4}, 30] (* Harvey P. Dale, Aug 16 2012 *)

Prog

(PARI) a(n)=2^(n%3)*10^(n\3) \\ Charles R Greathouse IV, Oct 22 2014
(Magma) [Seqint(Intseq(2^n, 8)): n in [0..30]]; // G. C. Greubel, Sep 10 2018
(Python)
def A004647(n): return int(oct(2**n)[2:]) # Chai Wah Wu, May 23 2022

Crossrefs

Sequence in context: A263993 A189585 A239346 * A265096 A236572 A283213

Adjacent sequences: A004644 A004645 A004646 * A004648 A004649 A004650

Keyword

nonn,base,easy

Author

N. J. A. Sloane

Status

approved