login
A055240
Number of bases in which n is not divisible by any of its digits.
9
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
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
KEYWORD
base,nonn,look
AUTHOR
Henry Bottomley, May 04 2000
STATUS
approved