id:A141095 - OEIS Search Results

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Number of unordered pairs of coprime nonprime numbers that sum to 2n.

+0
5

1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 1, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 3, 0, 1, 4, 1, 1, 1, 0, 3, 4, 1, 0, 4, 0, 4, 3, 0, 4, 5, 1, 1, 3, 1, 4, 6, 0, 0, 4, 1, 6, 6, 1, 5, 7, 1, 5, 3, 0, 8, 7, 0, 0, 10, 3, 9, 9, 0, 6, 5, 2, 8, 5, 2, 9, 10, 1, 5, 11, 2, 9, 12, 0, 3, 12, 4, 11, 5, 2, 12, 9, 1, 4, 14 (list; graph; listen)

	OFFSET	`1,17`
	COMMENT	`Nonprime numbers are 1 and the composite numbers. See A141097 for pairs of coprime composite numbers. It appears that a(n) > 0 except for the 26 values of 2n given in A141096.`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..10000` `Carlos Rivera, Conjecture 33: The Goldbach Temptation`
	EXAMPLE	`a(17)=2 because 34 = 1+33 = 9+25.`
	MATHEMATICA	`Table[cnt=0; Do[If[GCD[2n-i, i]==1 && !PrimeQ[i] && !PrimeQ[2n-i], cnt++ ], {i, 1, n, 2}]; cnt, {n, 100}]`
	CROSSREFS	`Cf. A141099, A141100.` `Sequence in context: A098055 A092111 A050317 this_sequence A159195 A099313 A097468` `Adjacent sequences: A141092 A141093 A141094 this_sequence A141096 A141097 A141098`
	KEYWORD	`nonn`
	AUTHOR	`T. D. Noe (noe(AT)sspectra.com), Jun 02 2008`

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.

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