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A004647 Powers of 2 written in base 8. 1
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 (list; graph; refs; listen; history; text; internal format)
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

REFERENCES

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

LINKS

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

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

FORMULA

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

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

CROSSREFS

Sequence in context: A127392 A189585 A239346 * A236572 A167030 A026644

Adjacent sequences:  A004644 A004645 A004646 * A004648 A004649 A004650

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified December 22 14:10 EST 2014. Contains 252364 sequences.