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

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

Crossrefs

Cf. A055238, A055239, A055241, A055242.

Sequence in context: A219240 A349612 A277080 * A174559 A334040 A273128

Adjacent sequences: A055237 A055238 A055239 * A055241 A055242 A055243

Keyword

base,nonn,look

Author

Henry Bottomley, May 04 2000

Status

approved