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A224715 The number of unordered partitions {a,b} of prime(n) such that a or b is a nonnegative composite and the other is prime. 1
0, 0, 0, 1, 4, 3, 6, 5, 8, 9, 8, 11, 12, 11, 14, 15, 16, 15, 18, 19, 18, 21, 22, 23, 24, 25, 24, 27, 26, 29, 30, 31, 32, 31, 34, 33, 36, 37, 38, 39, 40, 39, 42, 41, 44, 43, 46, 47, 48, 47, 50, 51, 50, 53, 54, 55, 56, 55, 58, 59, 58, 61, 62, 63, 62, 65, 66 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

J. Stauduhar, Table of n, a(n) for n = 1..5000

EXAMPLE

For n = 5, prime(5) = 11. The pairwise partitions of 11 are {{10, 1}, {9, 2}, {8, 3}, {7, 4}, {6, 5}} and four partitions meet the requirements: {9, 2}, {8, 3}, {7, 4}, {6, 5}, so a(5) =  4.

MATHEMATICA

nn = 100; mx = Prime[nn]; ps = Prime[Range[nn]]; notPs = Complement[Range[2, mx], ps]; t2 = Table[0, {Range[mx]}]; Do[s = i + j; If[s <= mx, t2[[s]]++], {i, ps}, {j, notPs}];  t2[[ps]] (* T. D. Noe, Apr 23 2013 *)

CROSSREFS

Subsequence of A224712.

Essentially the same as A062302.

Sequence in context: A242554 A219176 A251739 * A062302 A261723 A021233

Adjacent sequences:  A224712 A224713 A224714 * A224716 A224717 A224718

KEYWORD

nonn

AUTHOR

J. Stauduhar, Apr 22 2013

STATUS

approved

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Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)