id:A124044 - OEIS Search Results

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Number of ways to express 4n+3 as the sum of an odd square and twice a prime.

+0
1

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; listen)

	OFFSET	`0,4`
	COMMENT	`Is there any n > 19 for which a(n) = 0? There are no others below 50000.`
	REFERENCES	`Dudley, Underwood, "Mathematical Cranks", Mathematical Association of America 1992, p. 240` Sci.math thread `Conjecture in "Mathematical Cranks"`, November 2006
	LINKS	`T. D. Noe, Table of n, a(n) for n=0..10000`
	EXAMPLE	`43 + 3 = 15 = 1^2 + 27 = 3^2 + 2*3 so a(3) = 2`
	MAPLE	`f:= n -> nops(select(isprime, [seq]((4n+3-(2i+1)^2)/2, i=0..floor((sqrt(4*n+3)-1)/2)))): [seq](f(n), n=0..100);`
	CROSSREFS	`Sequence in context: A102096 A137866 A072203 this_sequence A059981 A033676 A095165` `Adjacent sequences: A124041 A124042 A124043 this_sequence A124045 A124046 A124047`
	KEYWORD	`easy,nonn`
	AUTHOR	`Robert B. Israel (israel(AT)math.ubc.ca), Nov 02 2006`

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Last modified July 26 23:19 EDT 2008. Contains 142293 sequences.

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