OFFSET
1,1
EXAMPLE
1365 = 3*5*7*13, and (1365+1)/2 = 683, a prime.
MATHEMATICA
t = Select[Range[1, 20000, 2], Map[Last, FactorInteger[#]] == Table[1, {4}] &]; Take[(t + 1)/2, 120] (* A234500*)
v = Flatten[Position[PrimeQ[(t + 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A234501 *)
(w + 1)/2 (* A234502 *) (* Peter J. C. Moses, Dec 23 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jan 01 2014
STATUS
approved