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A291563 Number of partitions of 2n into two prime parts or two nonprime parts. 1
1, 1, 1, 2, 4, 3, 4, 6, 6, 6, 8, 9, 9, 9, 11, 9, 13, 15, 10, 14, 16, 14, 16, 19, 18, 17, 21, 18, 20, 25, 18, 24, 27, 19, 26, 28, 25, 27, 32, 26, 28, 35, 29, 29, 39, 30, 32, 38, 30, 37, 41, 35, 37, 42, 38, 41, 47, 40, 40, 54, 38, 42, 53, 39, 48, 52, 46, 46 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..68.

Index entries for sequences related to partitions

FORMULA

a(n) = Sum_{i=1..n} [A010051(i) = A010051(2n-i)], where [] is the Iverson bracket.

a(n) = n - A291564(n).

MATHEMATICA

Table[Sum[KroneckerDelta[(PrimePi[k] - PrimePi[k - 1]), (PrimePi[2 n - k] - PrimePi[2 n - 1 - k])], {k, n}], {n, 80}]

CROSSREFS

Cf. A010051, A291564.

Sequence in context: A302707 A224714 A089169 * A178151 A087794 A050514

Adjacent sequences:  A291560 A291561 A291562 * A291564 A291565 A291566

KEYWORD

nonn,easy

AUTHOR

Wesley Ivan Hurt, Oct 20 2017

STATUS

approved

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Last modified May 24 18:34 EDT 2019. Contains 323534 sequences. (Running on oeis4.)