A055240 - OEIS

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A055240

Number of bases in which n is not divisible by any of its digits.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 3, 0, 3, 0, 1, 1, 6, 0, 3, 1, 2, 0, 7, 0, 7, 1, 4, 4, 7, 0, 9, 4, 6, 1, 11, 0, 13, 2, 3, 6, 17, 0, 11, 3, 8, 3, 18, 2, 13, 3, 11, 9, 22, 0, 18, 9, 8, 4, 15, 1, 23, 8, 16, 5, 24, 1, 24, 12, 11, 8, 24, 4, 29, 4, 15, 14, 31, 1, 22, 14, 21, 8, 34, 1, 23

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OFFSET

1,17

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

a(27)=2 because it is written as 27 in base 10 and 25 in base 11 and 27 is not divisible by 2, 5 or 7.

MAPLE

f:= proc(n)

nops(select(b -> not ormap(d -> d <> 0 and n mod d = 0, convert(n, base, b)), [$3 .. (n-1)/2]))

end proc:

map(f, [$1..100]); # Robert Israel, Jan 09 2024