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

1,1

Comments

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

Links

Table of n, a(n) for n=1..14.

Example

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

Mathematica

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

Crossrefs

Cf. A006882, A007749, A064401.

Sequence in context: A129216 A259536 A067796 * A015797 A293184 A368408

Adjacent sequences: A108417 A108418 A108419 * A108421 A108422 A108423

Keyword

nonn,more

Author

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

Extensions

More terms from Farideh Firoozbakht, Aug 19 2005

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

Status

approved