

A209402


Number of partitions of n into distinct primes except the prime factors of n.


1



1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 2, 1, 2, 2, 2, 1, 2, 4, 3, 2, 3, 1, 2, 6, 3, 8, 4, 2, 5, 3, 5, 10, 4, 3, 5, 13, 4, 14, 7, 4, 7, 18, 9, 12, 9, 6, 9, 25, 11, 10, 10, 9, 14, 34, 10, 38, 16, 11, 24, 14, 13, 49, 20, 18, 12, 60, 25, 66, 31, 17, 28
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OFFSET

0,17


COMMENTS

a(n) = 0 for n in {1, 2, 3, 4, 6, 11}, a(n) = 1 for n in {0, 5, 7, 8, 9, 10, 12, 13, 14, 15, 17, 21, 27}, a(n) = 2 for n in {16, 18, 19, 20, 22, 25, 28, 33}, a(n) = 3 for n in {24, 26, 30, 35, 39}, a(n) = 4 for n in {23, 32, 38, 42, 45}. The smallest n such that a(n) = 0, 1, 2, ... is 1, 0, 16, 24, 23, 34, 29, 44, 31, 48, 37, 54, 49, 41, 43, ... . Missing values are in {15, 19, 21, 22, 26, 33, 35, 36, 37, 39, 42, ... }.


LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..5000


FORMULA

a(p) = A000586(p)1 for any prime p.


EXAMPLE

a(5) = 1: [2,3].
a(7) = 1: [2,5].
a(16) = 2: [3,13], [5,11].
a(23) = 4: [3,7,13], [2,3,5,13], [5,7,11], [2,3,7,11].
a(24) = 3: [5,19], [7,17], [11,13].
a(29) = 6: [3,7,19], [2,3,5,19], [5,7,17], [2,3,7,17], [5,11,13], [2,3,11,13].
a(34) = 5: [3,31], [5,29], [11,23], [3,5,7,19], [3,7,11,13].


MAPLE

with (numtheory):
a:= proc(n) option remember; local b, l, f;
b:= proc(h, j) option remember;
`if`(h=0, 1, `if`(j<1, 0,
`if`(l[j]>h, 0, b(hl[j], j1)) +b(h, j1)))
end; forget (b);
f:= factorset(n);
l:= sort([({ithprime(i)$i=1..pi(n)} minus f)[]]);
b(n, nops(l))
end:
seq (a(n), n=0..300);


CROSSREFS

Cf. A000586, A208614.
Sequence in context: A232443 A118821 A118824 * A082641 A239140 A138553
Adjacent sequences: A209399 A209400 A209401 * A209403 A209404 A209405


KEYWORD

nonn,look


AUTHOR

Alois P. Heinz, Mar 22 2012


STATUS

approved



