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A344782
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Number of compositions of the n-th prime into a prime number of prime parts.
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3
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0, 0, 2, 5, 11, 23, 119, 237, 776, 6665, 16518, 207953, 892680, 1824445, 8374988, 96208461, 978217302, 2059770725, 18616884428, 78013141907, 158103168924, 1386674113487, 6734724875544, 82189835767618, 2013603833805429, 9101106147506177, 19147196940580651
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OFFSET
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1,3
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LINKS
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EXAMPLE
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a(3) = 2: [2,3], [3,2].
a(4) = 5: [5,2], [2,5], [3,2,2], [2,3,2], [2,2,3].
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MAPLE
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b:= proc(n, c) option remember; `if`(n=0, `if`(isprime(c),
1, 0), add(`if`(isprime(j), b(n-j, c+1), 0), j=2..n))
end:
a:= n-> b(ithprime(n), 0):
seq(a(n), n=1..31);
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MATHEMATICA
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b[n_, c_] := b[n, c] = If[n == 0, If[PrimeQ[c], 1, 0],
Sum[If[PrimeQ[j], b[n - j, c + 1], 0], {j, 2, n}]];
a[n_] := b[Prime[n], 0];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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