

A174813


a(n) = number whose product of digits equals a power of 3.


10



1, 3, 9, 11, 13, 19, 31, 33, 39, 91, 93, 99, 111, 113, 119, 131, 133, 139, 191, 193, 199, 311, 313, 319, 331, 333, 339, 391, 393, 399, 911, 913, 919, 931, 933, 939, 991, 993, 999, 1111, 1113, 1119, 1131, 1133, 1139, 1191, 1193, 1199, 1311, 1313, 1319, 1331
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OFFSET

1,2


COMMENTS

Equivalently, numbers whose decimal representation consists of digits from the set {1,3,9}.


LINKS



EXAMPLE

a(9)=39 is in the sequence because 3*9=3^3.


MATHEMATICA

Select[Range[2000], IntegerQ[Log[3, Times @@ (IntegerDigits[#])]] &]


PROG

(Haskell)
a174813 n = a174813_list !! (n1)
a174813_list = f [1] where
f ds = foldr (\d v > 10 * v + d) 0 ds : f (s ds)
s [] = [1]; s (9:ds) = 1 : s ds; s (d:ds) = 3*d : ds


CROSSREFS



KEYWORD

nonn,base


AUTHOR



STATUS

approved



