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A091629 Product of digits associated with A091628(n). Essentially the same as A007283. 12
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 the 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
Tanya Khovanova, Recursive Sequences
Carlos Rivera, Puzzle 251, Pointer primes, The Prime Puzzles and Problems Connection.
FORMULA
a(n) = 3 * 2^n = product of digits of A091628(n).
From Philippe Deléham, Nov 23 2008: (Start)
a(n) = 6*2^(n-1).
a(n) = 2*a(n-1), with a(1) = 6.
G.f.: 6*x/(1-2*x). (End)
E.g.f.: 3*(exp(2*x) - 1). - G. C. Greubel, Jan 05 2023
MATHEMATICA
3*2^Range[1, 60] (* Vladimir Joseph Stephan Orlovsky, Jun 09 2011 *)
PROG
(Magma) [3*2^n : n in [1..40]]; // Wesley Ivan Hurt, Jul 17 2020
(SageMath) [3*2^n for n in range(1, 51)] # G. C. Greubel, Jan 05 2023
CROSSREFS
Sequences of the form (2*m+1)*2^n: A000079 (m=0), A007283 (m=1), A020714 (m=2), A005009 (m=3), A005010 (m=4), A005015 (m=5), A005029 (m=6), A110286 (m=7), A110287 (m=8), A110288 (m=9), A175805 (m=10), A248646 (m=11), A164161 (m=12), A175806 (m=13), A257548 (m=15).
Sequence in context: A362487 A229926 A082505 * A089529 A300915 A001766
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 May 19 14:45 EDT 2024. Contains 372698 sequences. (Running on oeis4.)