A217707 Numbers n such that both 4*n-1 and 4*n+1 are composite.

14, 16, 19, 23, 29, 30, 31, 36, 40, 44, 46, 47, 51, 52, 54, 55, 59, 61, 62, 65, 72, 74, 75, 76, 80, 81, 82, 85, 86, 89, 91, 94, 98, 101, 103, 104, 106, 107, 109, 113, 118, 119, 121, 124, 128, 129, 132, 133, 134, 136, 138, 140, 145, 146, 149, 151, 156, 157, 159

Offset: 1

Author

Jayanta Basu, Mar 20 2013

Keywords

• nonn
• easy

Crossrefs

Cf. A060461, A045751.

Programs

Mathematica

Select[Range[200], ! PrimeQ[4 # - 1] && ! PrimeQ[4 # + 1] &]
Select[Range[200],AllTrue[4#+{1,-1},CompositeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Aug 11 2015 *)