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URL: https://oeis.org/A141095

⇱ A141095 - OEIS

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A141095
Number of unordered pairs of coprime nonprime numbers that sum to 2n.
8
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
OFFSET
1,17
COMMENTS
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
Carlos Rivera, Conjecture 33: The Goldbach Temptation, The Prime Puzzles & Problems Connection.
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
Sequence in context: A341027 A050317 A325223 * A175599 A179759 A257260
KEYWORD
nonn,look
AUTHOR
T. D. Noe, Jun 02 2008
STATUS
approved