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A234096
Integers of the form (p*q + 1)/2, where p and q are distinct primes.
6
8, 11, 17, 18, 20, 26, 28, 29, 33, 35, 39, 43, 44, 46, 47, 48, 56, 58, 60, 62, 65, 67, 71, 72, 73, 78, 80, 81, 89, 92, 93, 94, 101, 102, 103, 105, 107, 108, 109, 110, 111, 118, 119, 124, 125, 127, 130, 133, 134, 144, 146, 148, 150, 151, 152, 153, 155, 160
OFFSET
1,1
FORMULA
1 + A234093.
EXAMPLE
(3*5 + 1)/2 = 8, (3*7 + 1)/2 = 11.
MATHEMATICA
t = Select[Range[1, 7000, 2], Map[Last, FactorInteger[#]] == Table[1, {2}] &]; Take[(t + 1)/2, 120] (* A234096 *)
v = Flatten[Position[PrimeQ[(t + 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A233562 *)
(w + 1)/2 (* A234098 *) (* Peter J. C. Moses, Dec 23 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Dec 27 2013
STATUS
approved