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%I #9 Jan 25 2024 14:51:04
%S 1,2,3,9,52,84,85,86,87,105,106,170,191,255,345,352,357,358,360,361,
%T 362,366,368,369,381,394,406,409,410,415,422,444,462,479,486,492,496,
%U 497,501,503,504,505,506,507,509,510,511,553,597
%N Every base 4 digit of k is a base 7 digit of k.
%H Reinhard Zumkeller, <a href="/A037389/b037389.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Range[600],Complement[IntegerDigits[#,4],IntegerDigits[#,7]]=={}&] (* _Harvey P. Dale_, Jan 25 2024 *)
%o (Haskell)
%o import Data.List ((\\), nub)
%o a037389 n = a037389_list !! (n-1)
%o a037389_list = filter f [1..] where
%o f x = null $ nub (ds 4 x) \\ nub (ds 7 x)
%o ds b x = if x > 0 then d : ds b x' else [] where (x', d) = divMod x b
%o -- _Reinhard Zumkeller_, May 30 2013
%Y Cf. A037387, A037388, A037390, A037391, A037392.
%K nonn,base
%O 1,2
%A _Clark Kimberling_
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