A037389 Every base 4 digit of k is a base 7 digit of k.

1, 2, 3, 9, 52, 84, 85, 86, 87, 105, 106, 170, 191, 255, 345, 352, 357, 358, 360, 361, 362, 366, 368, 369, 381, 394, 406, 409, 410, 415, 422, 444, 462, 479, 486, 492, 496, 497, 501, 503, 504, 505, 506, 507, 509, 510, 511, 553, 597

Offset

1,2

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Mathematica

Select[Range[600], Complement[IntegerDigits[#, 4], IntegerDigits[#, 7]]=={}&] (* Harvey P. Dale, Jan 25 2024 *)

Prog

(Haskell)
import Data.List ((\\), nub)
a037389 n = a037389_list !! (n-1)
a037389_list = filter f [1..] where
   f x = null $ nub (ds 4 x) \\ nub (ds 7 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

Cf. A037387, A037388, A037390, A037391, A037392.

Sequence in context: A162099 A307069 A255739 * A037425 A226967 A181273

Adjacent sequences: A037386 A037387 A037388 * A037390 A037391 A037392

Keyword

nonn,base

Author

Clark Kimberling

Status

approved