

A171691


Number of unordered partitions {k1, k2} of n such that k1 and k2 are nonnegative nonprimes A141468.


1



1, 1, 0, 1, 1, 1, 1, 2, 2, 3, 1, 3, 2, 3, 3, 5, 2, 5, 3, 5, 4, 6, 3, 7, 5, 7, 5, 8, 5, 9, 6, 8, 7, 10, 7, 12, 7, 9, 9, 12, 8, 13, 9, 12, 10, 13, 9, 15, 11, 15, 11, 15, 11, 17, 13, 16, 13, 17, 13, 20, 14, 16, 15, 20, 15, 22, 15, 18, 17, 22, 16, 23, 17, 21, 18, 23, 18, 26, 18, 23
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OFFSET

1,8


LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..10000


EXAMPLE

a(1) = 1 because 1 = 0 + 1.
a(2) = 1 because 2 = 1 + 1.
a(3) = 0.
a(4) = 1 because 4 = 0 + 4.
a(5) = 1 because 5 = 1 + 4.
a(6) = 1 because 6 = 0 + 6.
a(7) = 1 because 7 = 1 + 6.
a(8) = 2 because 8 = 0 + 8 = 4 + 4.


PROG

(PARI) a(n)={sum(i=0, n\2, (i<2  !isprime(i)) && !isprime(ni))} \\ Andrew Howroyd, Jan 05 2020


CROSSREFS

Cf. A062610, A141468, A224708.
Sequence in context: A233431 A160650 A304092 * A088904 A241568 A047972
Adjacent sequences: A171688 A171689 A171690 * A171692 A171693 A171694


KEYWORD

nonn


AUTHOR

JuriStepan Gerasimov, Dec 15 2009


EXTENSIONS

Name clarified and terms a(55) and beyond from Andrew Howroyd, Jan 05 2020


STATUS

approved



