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A091629 Product of digits associated with A091628(n). Essentially the same as A007283. 9
6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072, 6144, 12288, 24576, 49152, 98304, 196608, 393216, 786432, 1572864, 3145728, 6291456, 12582912, 25165824, 50331648, 100663296, 201326592, 402653184, 805306368, 1610612736, 3221225472 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Sequence arising in Farideh Firoozbakht's solution to Prime Puzzle 251 - 23 is only pointer prime (A089823) not containing digit "1".

The monotonic increasing value of successive product of digits strongly suggests that in successive n the digit 1 must be present.

LINKS

Table of n, a(n) for n=1..30.

Tanya Khovanova, Recursive Sequences

Carlos Rivera's Prime Puzzles and Problems Connection, Puzzle 251, Pointer primes

Index entries for linear recurrences with constant coefficients, signature (2).

FORMULA

a(n) = 2^n*3 = product of digits of A091628(n).

a(n) = 6*2^(n-1). a(n)=2*a(n-1), n>1, a(1)=6. G.f.: 6*x/(1-2x). - Philippe Deléham, Nov 23 2008

EXAMPLE

a(1) = 2*3 = 6.

MATHEMATICA

3*2^Range[1, 60] (* Vladimir Joseph Stephan Orlovsky, Jun 09 2011 *)

CROSSREFS

Cf. A089823, A091628, A091630, A091631, A091632.

Similar to A003945, A007283, A042950, A058764, A087009.

Sequence in context: A160728 A229926 A082505 * A089529 A001766 A110959

Adjacent sequences:  A091626 A091627 A091628 * A091630 A091631 A091632

KEYWORD

base,easy,nonn

AUTHOR

Enoch Haga, Jan 24 2004

EXTENSIONS

Edited and extended by Ray Chandler, Feb 07 2004

STATUS

approved

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Last modified June 24 20:12 EDT 2017. Contains 288707 sequences.