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Search: id:A068307
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| A068307 |
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From Goldbach problem: number of decompositions of n into a sum of three primes. |
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+0
10
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| 0, 0, 0, 0, 0, 1, 1, 1, 2, 1, 2, 2, 2, 1, 3, 2, 4, 2, 3, 2, 5, 2, 5, 3, 5, 3, 7, 3, 7, 2, 6, 3, 9, 2, 8, 4, 9, 4, 10, 2, 11, 3, 10, 4, 12, 3, 13, 4, 12, 5, 15, 4, 16, 3, 14, 5, 17, 3, 16, 4, 16, 6, 19, 3, 21, 5, 20, 6, 20, 2, 22, 5, 21, 6, 22, 5, 28, 5, 24, 7, 25, 4, 29, 5, 27, 8, 29, 5, 33, 4, 29
(list; graph; listen)
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OFFSET
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1,9
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COMMENT
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For even n>2: a(n) = A061358(n-2). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 08 2009]
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LINKS
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Robert G. Wilson v, Table of n, a(n) for n=1..36000
Wikipedia, Goldbach's conjecture.
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MATHEMATICA
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f[n_] := Block[{c = 0, lmt = PrimePi@ Floor[n/2], p, q}, Do[p = Prime@ i; q = Prime@ j; r = n - p - q; If[ PrimeQ@ r && r >= p, c++ ], {i, lmt}, {j, i}]; c]; Array[f, 91] (* from Robert G. Wilson v, (rgwv(AT)rgwv.com), Apr 13 2008 *)
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CROSSREFS
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Bisections: A045917, A054860. Cf. A002375, A061358, A059998.
First occurrence: A139321. Records: A139322.
Sequence in context: A001227 A060764 A105149 this_sequence A158946 A023645 A054571
Adjacent sequences: A068304 A068305 A068306 this_sequence A068308 A068309 A068310
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KEYWORD
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easy,nonn
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AUTHOR
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Naohiro Nomoto (n_nomoto(AT)yabumi.com), Feb 24 2002
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 10 2002
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