login
A186445
The number of partitions of n in which the first part is at least four times larger than the second part.
2
1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 8, 10, 13, 16, 20, 25, 31, 38, 47, 57, 70, 85, 103, 124, 150, 180, 216, 258, 308, 366, 436, 516, 611, 721, 850, 1000, 1176, 1378, 1614, 1886, 2203, 2567, 2990, 3474, 4034, 4677, 5417, 6264, 7239, 8351, 9628
OFFSET
0,6
FORMULA
a(n) = p(n)-p(n-2)-p(n-3)-p(n-4)+p(n-5)+p(n-6)+p(n-7)-p(n-9), where p(n) = A000041(n).
EXAMPLE
a(8) = #{8, 7+1, 6+1+1, 5+1+1+1, 4+1+1+1+1} = 5.
a(10) = #{10, 9+1, 8+2, 8+1+1, 7+1+1+1, 6+1+1+1+1, 5+1+1+1+1+1, 4+1+1+1+1+1+1} = 8.
CROSSREFS
Cf. A000041.
Partial sums of A185325.
Sequence in context: A276828 A309715 A241089 * A080078 A036415 A054961
KEYWORD
nonn
AUTHOR
Mircea Merca, Feb 21 2011
STATUS
approved