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A037391
Numbers k such that every base-4 digit of k is a base-9 digit of k.
6
1, 2, 3, 81, 84, 85, 93, 101, 102, 105, 106, 110, 162, 168, 170, 174, 190, 191, 243, 244, 252, 253, 254, 255, 325, 341, 650, 750, 758, 768, 837, 885, 894, 918, 919, 921, 922, 923, 925, 926, 939, 957, 972, 973, 974, 975, 976, 977
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[1000], SubsetQ[IntegerDigits[#, 9], IntegerDigits[#, 4]]&] (* Harvey P. Dale, Jul 12 2024 *)
PROG
(Haskell)
import Data.List ((\\), nub)
a037391 n = a037391_list !! (n-1)
a037391_list = filter f [1..] where
f x = null $ nub (ds 4 x) \\ nub (ds 9 x)
ds b x = if x > 0 then d : ds b x' else [] where (x', d) = divMod x b
-- Reinhard Zumkeller, May 30 2013
CROSSREFS
KEYWORD
nonn,base
STATUS
approved