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.

Showing 1-3 of 3 results.

A261787 a(n) is the smallest nonzero number that is not a substring of n in ternary representation.

Original entry on oeis.org

1, 2, 1, 2, 2, 3, 1, 3, 1, 2, 2, 4, 2, 2, 3, 3, 3, 3, 1, 3, 1, 4, 3, 3, 1, 3, 1, 2, 2, 4, 2, 2, 4, 4, 4, 4, 2, 2, 5, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 3, 3, 3, 1, 3, 1, 4, 3, 3, 1, 3, 1, 4, 4, 4, 5, 3, 3, 3, 3, 3, 1, 3, 1, 4, 3, 3, 1, 3, 1, 2, 2, 4, 2, 2
Offset: 0

Views

Author

Reinhard Zumkeller, Sep 01 2015

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List (isInfixOf)
    a261787 x = f $ tail a030341_tabf where
       f (cs:css) = if isInfixOf cs (a030341_row x)
                       then f css else foldr (\d v -> 3 * v + d) 0 cs
    
  • PARI
    ts(n) = Str(fromdigits(digits(n, 3)));
    a(n) = my(s=ts(n), k=1); while (#strsplit(s, ts(k)) != 1, k++); k; \\ Michel Marcus, Feb 05 2022

Formula

A261789(n) = a(A261786(n)).

A261793 Successively add the smallest number that is not a substring in decimal representation.

Original entry on oeis.org

1, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 19, 21, 24, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 48, 49, 50, 51, 53, 54, 55, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 80, 81
Offset: 1

Views

Author

Reinhard Zumkeller, Sep 01 2015

Keywords

Crossrefs

Cf. A031298, A261794, A261795 (first differences), A261806, A260273, A261786

Programs

  • Haskell
    a261793 n = a261793_list !! (n-1)
    a261793_list = iterate (\x -> x + a261794 x) 1

A261795 First differences of A261793.

Original entry on oeis.org

2, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2
Offset: 1

Views

Author

Reinhard Zumkeller, Sep 01 2015

Keywords

Comments

a(n) = A261794(A261793(n)).

Crossrefs

Programs

  • Haskell
    a261795 n = a261795_list !! (n-1)
    a261795_list = zipWith (-) (tail a261793_list') a261793_list'
Showing 1-3 of 3 results.