A234499 Primes of the form (p*q*r*s - 1)/2, where p, q, r,s are distinct primes.

577, 997, 1567, 1627, 1657, 2467, 2557, 2593, 3391, 3517, 3547, 3607, 3697, 3727, 3877, 4231, 4273, 4357, 4933, 5167, 5227, 5347, 5407, 5527, 5857, 5869, 6121, 6451, 7297, 7417, 7927, 8053, 8179, 8389, 8431, 8521, 8627, 8677, 9091, 9397, 9439, 9547, 9613

Offset: 1

Author

Clark Kimberling, Jan 01 2014

Keywords

• nonn
• easy

Examples

			(See A234498.)
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A234105, A234499, A234500.

Programs

Mathematica

t = Select[Range[1, 20000, 2], Map[Last, FactorInteger[#]] == Table[1, {4}] &]; Take[(t - 1)/2, 120] (* A234105 *)
v = Flatten[Position[PrimeQ[(t - 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}]  (* A234498 *)
(w - 1)/2 (* A234499 *) (* Peter J. C. Moses, Dec 23 2013 *)
Module[{upto=10000,maxp},maxp=Ceiling[PrimePi[upto/30]];Select[Sort[ Select[ (#-1)/2&/@Times@@@Subsets[Prime[Range[maxp]],{4}], PrimeQ]], #<=upto&]] (* Harvey P. Dale, Feb 07 2016 *)