cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A037385 Numbers k such that every base-3 digit of k is a base-9 digit of k.

Original entry on oeis.org

1, 2, 9, 13, 18, 26, 81, 82, 83, 84, 85, 90, 99, 108, 117, 121, 162, 163, 164, 168, 170, 171, 180, 216, 234, 242, 244, 252, 325, 333, 488, 504, 650, 666, 729, 730, 731, 732, 733, 738, 739, 740, 741, 742, 747, 748, 749, 750, 751
Offset: 1

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Programs

  • Haskell
    import Data.List ((\\), nub)
    a037385 n = a037385_list !! (n-1)
    a037385_list = filter f [1..] where
       f x = null $ nub (ds 3 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
  • Mathematica
    Select[Range[1000],SubsetQ[IntegerDigits[#,9],IntegerDigits[#,3]]&] (* Harvey P. Dale, Dec 19 2015 *)