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

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

0,2

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Formula

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

Prog

(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

Crossrefs

Cf. A007089, A030341, A261789, A261786, A261461, A261794.

Sequence in context: A202389 A210868 A176853 * A302480 A329656 A000374

Adjacent sequences: A261784 A261785 A261786 * A261788 A261789 A261790

Keyword

nonn,base

Author

Reinhard Zumkeller, Sep 01 2015

Status

approved