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A197181
Numbers that are a divisor of the product of the factorials of their digits in decimal representation.
4
1, 2, 3, 4, 5, 6, 7, 8, 9, 15, 16, 18, 24, 28, 36, 45, 48, 60, 64, 70, 72, 75, 80, 84, 90, 96, 98, 128, 144, 168, 175, 180, 189, 192, 256, 280, 288, 360, 378, 384, 448, 480, 486, 567, 576, 588, 640, 648, 672, 675, 720, 729, 756, 768, 784, 840, 864, 875, 882
OFFSET
1,2
LINKS
EXAMPLE
a(10)=15: A066459(15) = 1!*5! = 120 = 15 * 8;
a(11)=16: A066459(16) = 1!*6! = 720 = 16 * 45;
17 is not a term because 5040 mod 17 = 8, A066459(16) = 5040;
a(12)=18: A066459(15) = 1!*8! = 40320 = 18 * 2240.
MATHEMATICA
Select[Range[900], IntegerQ[Times@@(IntegerDigits[#]!)/#]&] (* Harvey P. Dale, Jul 07 2019 *)
PROG
(Haskell)
import Data.List (elemIndices)
a197181 n = a197181_list !! (n-1)
a197181_list = map (+ 1) $ elemIndices 0 $
zipWith mod (map a066459 [1..]) [1..]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Oct 11 2011
STATUS
approved