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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 (list; graph; refs; listen; history; text; internal format)
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(n-i))} \\ Andrew Howroyd, Jan 05 2020

CROSSREFS

Cf. A062610, A141468, A224708.

Sequence in context: A160650 A304092 A339669 * A088904 A241568 A335017

Adjacent sequences: A171688 A171689 A171690 * A171692 A171693 A171694

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Dec 15 2009

EXTENSIONS

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

STATUS

approved

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Last modified November 29 18:13 EST 2022. Contains 358431 sequences. (Running on oeis4.)