A103800 Indices n such that A019565(n)-2 is prime.

4, 6, 8, 10, 14, 18, 20, 22, 26, 28, 30, 32, 34, 38, 40, 42, 54, 58, 60, 62, 68, 76, 78, 86, 88, 98, 100, 102, 106, 110, 126, 128, 134, 136, 138, 142, 158, 162, 174, 188, 190, 194, 196, 202, 210, 218, 222, 230, 234, 238, 240, 254, 258, 260, 272, 274, 278, 292, 294

Offset: 1

Author

Lei Zhou, Feb 22 2005

Keywords

• easy
• nonn

Examples

			A019565(0)=1, 1-2=-1 is not prime;
A019565(1)=2, 2-2=0 is not prime;
...
A019565(4)=5, 5-2=3 is prime, so a(1)=4;
		

Crossrefs

Cf. A019565, A103799.

Programs

Mathematica

A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp = A019565[n] - 2; If[PrimeQ[cp], Print[n]], {n, 0, 1000}]