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A124044
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Number of ways to express 4n+3 as the sum of an odd square and twice a prime.
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1
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0, 1, 1, 2, 1, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 3, 1, 3, 2, 0, 4, 4, 2, 4, 1, 2, 4, 2, 2, 3, 2, 3, 4, 3, 1, 6, 3, 1, 4, 3, 1, 6, 2, 3, 3, 4, 2, 3, 4, 1, 6, 4, 1, 6, 2, 2, 7, 3, 2, 4, 4, 2, 4, 4, 2, 6, 2, 2, 4, 3, 3, 6, 1, 2, 6, 5, 3, 5, 4, 1, 5, 6, 1, 6, 2, 3, 6, 3, 2, 4, 4, 3, 6, 5, 1, 9, 4, 2, 8, 3, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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COMMENTS
| Is there any n > 19 for which a(n) = 0? There are no others below 50000.
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REFERENCES
| Dudley, Underwood, "Mathematical Cranks", Mathematical Association of America 1992, p. 240
Sci.math thread `Conjecture in "Mathematical Cranks"`, November 2006
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LINKS
| T. D. Noe, Table of n, a(n) for n=0..10000
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EXAMPLE
| 4*3 + 3 = 15 = 1^2 + 2*7 = 3^2 + 2*3 so a(3) = 2
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MAPLE
| f:= n -> nops(select(isprime, [seq]((4*n+3-(2*i+1)^2)/2, i=0..floor((sqrt(4*n+3)-1)/2)))): [seq](f(n), n=0..100);
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CROSSREFS
| Sequence in context: A102096 A137866 A072203 * A059981 A033676 A095165
Adjacent sequences: A124041 A124042 A124043 * A124045 A124046 A124047
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KEYWORD
| easy,nonn
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AUTHOR
| Robert B. Israel (israel(AT)math.ubc.ca), Nov 02 2006
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