

A234716


Number of odd composite integers k, such that n1 < k < 2n2.


1



0, 0, 0, 0, 0, 1, 1, 1, 2, 1, 1, 2, 2, 3, 4, 3, 3, 4, 5, 5, 6, 5, 5, 6, 6, 6, 7, 6, 7, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 11, 11, 12, 13, 12, 13, 14, 15, 14, 15, 14, 14, 15, 15, 14, 15, 14, 15, 16, 17, 18, 19, 19, 19, 19, 19, 20, 21, 20, 20, 21, 22, 23
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OFFSET

1,9


COMMENTS

Number of partitions of 2n into two odd parts such that the largest part is an odd composite less than 2n2.


LINKS



FORMULA

a(n) = floor((n1)/2)  pi(2n3)  pi(n1).


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).


MAPLE

with(numtheory); A234716:=n>floor((n1)/2)  pi(2*n3) + pi(n1); seq(A234716(n), n=1..100);


MATHEMATICA

Table[Floor[(n  1)/2]  PrimePi[2 n  3] + PrimePi[n  1], {n, 100}]


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



