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.

A106371 Representation of n in base b, where b is minimal such that n contains no zeros: b = A106370(n).

Original entry on oeis.org

1, 2, 11, 11, 12, 12, 111, 22, 21, 22, 23, 22, 111, 112, 1111, 121, 122, 33, 34, 32, 111, 211, 212, 44, 221, 222, 123, 44, 131, 132, 11111, 112, 113, 114, 55, 121, 211, 212, 213, 1111, 1112, 222, 1121, 1122, 231, 232, 233, 143, 1211, 1212, 123, 1221, 1222, 312
Offset: 1

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Author

Reinhard Zumkeller, May 01 2005

Keywords

Comments

In decimal representation feasible only for bases <= 10; A106371(11) = 360 = 2*11^2 + 10*11^1 + 8*11^0 is the first number which cannot be written zerofree with digits 1..9 in base 11. Therefore this sequence is finite with exactly 359 terms. - Reinhard Zumkeller, Apr 12 2015

Crossrefs

Programs

  • Haskell
    a106371 n = a106371_list !! (n-1)
    a106371_list = map fromJust $ takeWhile (/= Nothing) $ map f [1..] where
       f n = g 2 n where
         g b x = h x 0 where
           h 0 y = if b <= 10 then Just (a004086 y) else Nothing
           h z y = if r == 0 then g (b + 1) n else h z' (10 * y + r)
                   where (z', r) = divMod z b
    -- Reinhard Zumkeller, Apr 12 2015