OFFSET
1,9
COMMENTS
Number of partitions of 2n into two odd parts such that the largest part is an odd composite less than 2n-2.
FORMULA
a(n) = floor((n-1)/2) - pi(2n-3) - pi(n-1).
EXAMPLE
a(9) = 2; There are two partitions of 2(9) = 18 into two odd parts such that the largest part is an odd composite less than 2(9)-2 = 16: (15,3) and (9,9).
MATHEMATICA
Table[Floor[(n - 1)/2] - PrimePi[2 n - 3] + PrimePi[n - 1], {n, 100}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Dec 29 2013
STATUS
approved