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Search: id:A085755
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| A085755 |
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Number of partitions of n into a prime number of prime parts. |
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+0
1
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| 1, 1, 2, 2, 2, 3, 4, 3, 4, 5, 6, 8, 8, 9, 9, 12, 12, 16, 16, 19, 19, 26, 24, 31, 29, 39, 35, 50, 44, 61, 55, 74, 67, 93, 80, 111, 99, 136, 119, 166, 145, 197, 179, 239, 213, 292, 255, 342, 310, 409, 365, 492, 436, 577, 524, 682, 614, 814, 724, 947, 865, 1113, 1007, 1314
(list; graph; listen)
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OFFSET
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4,3
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EXAMPLE
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a(20)=12 because there are 12 partitions of 20 into a prime number of prime parts: 2+3+3+3+3+3+3=2+2+2+3+3+3+5=2+2+2+2+2+5+5=2+2+2+2+2+3+7=2+3+5+5+5=
2+3+3+5+7=2+2+2+7+7=2+2+2+3+11=2+7+11=2+5+13=7+13=3+17.
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MAPLE
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b:= proc(n, i, t) if n<0 then 0 elif n=0 then `if` (isprime(t), 1, 0) elif i=1 then `if` (irem(n, 2)=0 and isprime(t +n/2), 1, 0) else b(n, i, t):= b(n-ithprime(i), i, t+1) +b(n, i-1, t) fi end: a:= proc(n) local i; for i while ithprime(i)<n do od; b(n, i, 0) end: seq (a(n), n=4..70); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Apr 30 2009]
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CROSSREFS
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Cf. A000607, A038499.
Equals 2 * A005773, n>0.
Sequence in context: A055034 A112184 A112213 this_sequence A138304 A054860 A098745
Adjacent sequences: A085752 A085753 A085754 this_sequence A085756 A085757 A085758
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 21 2003
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