A234096 Integers of the form (p*q + 1)/2, where p and q are distinct primes.

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

Links

Table of n, a(n) for n=1..58.

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

Cf. A234093, A233562, A234098.

Sequence in context: A065348 A155717 A188197 * A111254 A127271 A118549

Adjacent sequences: A234093 A234094 A234095 * A234097 A234098 A234099

Keyword

nonn,easy

Author

Clark Kimberling, Dec 27 2013

Status

approved