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A163656
Arithmetic mean of the n-th and (n+1)st twin prime member A001097.
3
4, 6, 9, 12, 15, 18, 24, 30, 36, 42, 51, 60, 66, 72, 87, 102, 105, 108, 123, 138, 144, 150, 165, 180, 186, 192, 195, 198, 213, 228, 234, 240, 255, 270, 276, 282, 297, 312, 330, 348, 384, 420, 426, 432, 447, 462, 492, 522, 546, 570, 585, 600, 609, 618, 630, 642
OFFSET
1,1
FORMULA
a(n) = (A001097(n) + A001097(n+1))/2.
EXAMPLE
a(1) = 4 = (3+5)/2.
MATHEMATICA
t = Select[Prime[Range[500]], PrimeQ[# - 2] || PrimeQ[# + 2] &]; (Most[t] + Rest[t])/2 (* T. D. Noe, Aug 07 2012 *)
CROSSREFS
Cf. A014574 (bisection).
Sequence in context: A162735 A024675 A274135 * A134678 A100915 A144922
KEYWORD
nonn
AUTHOR
EXTENSIONS
35 replaced by 36 - R. J. Mathar, Aug 06 2009
STATUS
approved