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A037403
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Numbers k such that every base-7 digit of k is a base-9 digit of k.
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4
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1, 2, 3, 4, 5, 6, 31, 99, 106, 107, 195, 198, 248, 257, 284, 297, 321, 498, 514, 749, 750, 751, 758, 767, 785, 936, 939, 940, 943, 950, 968, 996, 1028, 1086, 1088, 1110, 1163, 1200, 1218, 1254, 1453, 1471, 1498, 1500, 1502, 1507
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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LINKS
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PROG
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(Haskell)
import Data.List ((\\), nub)
a037403 n = a037403_list !! (n-1)
a037403_list = filter f [1..] where
f x = null $ nub (ds 7 x) \\ nub (ds 9 x)
ds b x = if x > 0 then d : ds b x' else [] where (x', d) = divMod x b
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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