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A132080
Numbers having in decimal representation no common digits with all their proper divisors.
3
2, 3, 4, 5, 6, 7, 8, 9, 23, 27, 29, 34, 37, 38, 43, 46, 47, 49, 53, 54, 56, 57, 58, 59, 67, 68, 69, 73, 76, 78, 79, 83, 86, 87, 89, 97, 223, 227, 229, 233, 239, 247, 249, 257, 259, 263, 267, 269, 277, 283, 289, 293, 307, 323, 329, 334, 337, 347, 349, 353, 356, 358, 359
OFFSET
1,1
COMMENTS
A038603 is a subsequence.
LINKS
Eric Weisstein's World of Mathematics, Proper Divisor
EXAMPLE
Proper divisors of a(20)=54: {1, 2, 3, 6, 9, 18, 27}
with set of digits {1,2,3,6,7,8,9} containing neither 4 nor 5.
PROG
(Haskell)
import Data.List (intersect)
a132080 n = a132080_list !! (n-1)
a132080_list = [x | x <- [2..], all null $
map (show x `intersect`) $ map show $ a027751_row x]
-- Reinhard Zumkeller, Oct 06 2012
(PARI) is(n)=my(D=Set(digits(n))); fordiv(n, d, if(#setintersect(D, Set(digits(d))), return(d==n&&n>1))) \\ Charles R Greathouse IV, Dec 01 2013
CROSSREFS
Subsequence of A052383.
Sequence in context: A061672 A272814 A322516 * A307636 A373722 A048386
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Aug 09 2007
STATUS
approved