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A199322
Number of twin prime numbers of the form n*(n+1) + 2*k-3 and n*(n+1) + 2*k-1 with k = 1 to n+1.
1
1, 1, 2, 0, 1, 1, 1, 1, 2, 0, 2, 1, 2, 1, 2, 1, 1, 1, 0, 2, 1, 1, 1, 3, 1, 0, 1, 3, 1, 0, 3, 2, 1, 1, 4, 0, 2, 2, 2, 2, 2, 2, 2, 2, 5, 1, 3, 1, 0, 2, 4, 2, 0, 2, 2, 3, 4, 3, 3, 2, 2, 4, 4, 5, 1, 4, 2, 3, 2, 3, 1, 1, 5, 3, 2, 2, 2, 3, 2, 2, 6, 4, 1, 2, 3, 4
OFFSET
1,3
COMMENTS
0.66*n/log(n)^2 is a good approximation for a(n) as n increases
MATHEMATICA
Table[m = n*(n+1); Length[Select[Range[n+1], PrimeQ[m + 2*#-3] && PrimeQ[m + 2*#-1] &]], {n, 100}] (* T. D. Noe, Nov 07 2011 *)
CROSSREFS
Sequence in context: A025905 A115861 A282355 * A351567 A284203 A375106
KEYWORD
nonn
AUTHOR
Pierre CAMI, Nov 07 2011
STATUS
approved