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A054860
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Number of ways of writing 2n+1 as p+q+r where p,q,r are primes with p <= q <= r.
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5
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0, 0, 0, 1, 2, 2, 2, 3, 4, 3, 5, 5, 5, 7, 7, 6, 9, 8, 9, 10, 11, 10, 12, 13, 12, 15, 16, 14, 17, 16, 16, 19, 21, 20, 20, 22, 21, 22, 28, 24, 25, 29, 27, 29, 33, 29, 33, 35, 34, 30, 38, 36, 35, 43, 38, 37, 47, 42, 43, 50, 46, 47, 53, 50, 45, 57, 54, 47, 62, 53, 49, 65, 59, 55, 68
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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COMMENTS
| Every sufficiently large odd number is the sum of three primes (th. by Vinogradov, 1937). Goldbach's conjecture requires three ODD primes and then a(n) > 0 for n > 2 is weaker.
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REFERENCES
| G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979, appendix 3.
Wolfgang Schwarz, Einfuehrung in Methoden und Ergebnisse der Primzahltheorie, Bibliographisches Institut Mannheim, 1969, ch. 7.
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LINKS
| T. D. Noe, Table of n, a(n) for n=0..999 [b-file corrected by N. J. A. Sloane, Oct 04 2010]
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EXAMPLE
| 7=2+2+3 so a(3)=1; 9=2+2+5=3+3+3 so a(4)=2, 11=2+2+7=3+3+5 so a(5)=2.
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CROSSREFS
| Cf. A007963.
Sequence in context: A112213 A085755 A138304 * A098745 A029158 A156197
Adjacent sequences: A054857 A054858 A054859 * A054861 A054862 A054863
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KEYWORD
| nonn
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AUTHOR
| James A. Sellers (sellersj(AT)math.psu.edu), May 25 2000
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