login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A028846 Numbers n such that product of digits of n is a power of 2. 16
1, 2, 4, 8, 11, 12, 14, 18, 21, 22, 24, 28, 41, 42, 44, 48, 81, 82, 84, 88, 111, 112, 114, 118, 121, 122, 124, 128, 141, 142, 144, 148, 181, 182, 184, 188, 211, 212, 214, 218, 221, 222, 224, 228, 241, 242, 244, 248, 281, 282, 284, 288, 411, 412, 414, 418, 421, 422, 424, 428, 441, 442, 444, 448 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers using only digits 1, 2, 4, and 8. - Michel Lagneau, Dec 01 2010

LINKS

Bo Gyu Jeong, Table of n, a(n) for n = 1..5000

EXAMPLE

28 is in the sequence because 2*8=2^4. - Michel Lagneau, Dec 01 2010

MATHEMATICA

Select[Range[1000], IntegerQ[Log[2, Times @@ (IntegerDigits[#])]] &] (* Michel Lagneau, Dec 01 2010 *)

PROG

(Haskell)

a028846 n = a028846_list !! (n-1)

a028846_list = f [1] where

   f ds = foldr (\d v -> 10 * v + d) 0 ds : f (s ds)

   s [] = [1]; s (8:ds) = 1 : s ds; s (d:ds) = 2*d : ds

-- Reinhard Zumkeller, Jan 13 2014

CROSSREFS

Cf. A007954, A028889, A028838.

Cf. A174813, A061426.

Sequence in context: A028889 A235700 A174781 * A274924 A080152 A136994

Adjacent sequences:  A028843 A028844 A028845 * A028847 A028848 A028849

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Scott Lindhurst (ScottL(AT)alumni.princeton.edu)

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 24 22:23 EDT 2019. Contains 324337 sequences. (Running on oeis4.)