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.

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A030283 a(0) = 0; for n>0, a(n) is the smallest number greater than a(n-1) which does not use any digit used by a(n-1).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 22, 30, 41, 50, 61, 70, 81, 90, 111, 200, 311, 400, 511, 600, 711, 800, 911, 2000, 3111, 4000, 5111, 6000, 7111, 8000, 9111, 20000, 31111, 40000, 51111, 60000, 71111, 80000, 91111, 200000, 311111, 400000, 511111, 600000
Offset: 0

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Author

Keywords

Comments

The sequence is infinite.

Crossrefs

Programs

  • Haskell
    a030283 n = a030283_list !! n
    a030283_list = 0 : f 1 9 0 where
       f u v w = w' : f u' v' w' where
         w' = until (> w) ((+ v) . (* 10)) u
         (u',v') = h u v
         h 1 0 = (2,2); h 9 0 = (1,1); h 9 1 = (2,0); h 9 9 = (1,0)
         h u 2 = (u+1,0); h u v = (u+1,1-v)
    -- Reinhard Zumkeller, May 03 2012
  • Mathematica
    a = {0}; For[n = 1, n < 1000000, n++, If[Length[Intersection[IntegerDigits[n], IntegerDigits[a[[ -1]]]]] == 0, AppendTo[a, n]]]; a (* Stefan Steinerberger, May 30 2007 *)

Formula

a(n) = a(n-2) + 10*a(n-8) - 10*a(n-10) for n > 29. - Nicolas Bělohoubek, Jul 01 2024

Extensions

Edited by N. J. A. Sloane at the suggestion of Rick L. Shepherd, Sep 27 2007
Definition clarified by Harvey P. Dale, Oct 19 2012

A229364 a(1) = 1; for n > 1: a(n) = smallest odd number greater than a(n-1) which does not use any digit used by a(n-1).

Original entry on oeis.org

1, 3, 5, 7, 9, 11, 23, 41, 53, 61, 73, 81, 93, 101, 223, 401, 523, 601, 723, 801, 923, 1001, 2223, 4001, 5223, 6001, 7223, 8001, 9223, 10001, 22223, 40001, 52223, 60001, 72223, 80001, 92223, 100001, 222223, 400001, 522223, 600001, 722223, 800001, 922223
Offset: 1

Views

Author

Reinhard Zumkeller, Sep 21 2013

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List (intersect)
    a229364 n = a229364_list !! (n-1)
    a229364_list = f "" [1, 3 ..] where
       f xs (o:os) = if null $ intersect xs ys then o : f ys os else f xs os
                     where ys = show o

Formula

From Chai Wah Wu, Oct 21 2024: (Start)
a(n) = a(n-2) + 10*a(n-8) - 10*a(n-10) for n > 15.
G.f.: x*(-10*x^14 - 20*x^13 - 20*x^12 - 20*x^11 - 20*x^10 - 10*x^9 + 20*x^8 + 30*x^7 + 14*x^6 + 4*x^5 + 4*x^4 + 4*x^3 + 4*x^2 + 3*x + 1)/((x - 1)*(x + 1)*(10*x^8 - 1)). (End)
Showing 1-2 of 2 results.