A108420 Numbers k such that k!! - prime(k) is prime.

14, 20, 54, 56, 144, 206, 212, 436, 1610, 4450, 4512, 5202, 6684, 14318

Offset: 1

Author

Amineh Farzannia (afarzannia(AT)yahoo.com), Jul 06 2005

Keywords

• nonn
• more

Comments

There is no further term up to 8800. - Farideh Firoozbakht, Aug 19 2005

Examples

			14 is a term since 14!! - prime(14) = 645120 - 43 = 645077 is prime.
		

Crossrefs

Cf. A006882, A007749, A064401.

Programs

Mathematica

Select[Range[1610], PrimeQ[ #!! - Prime[ # ]] &]

Extensions

More terms from Farideh Firoozbakht, Aug 19 2005

Name corrected, term 3 removed, and a(14) from Michael S. Branicky, Jan 03 2025