A076211 Numbers k such that (-k!! + (k+1)!! - 1)/2 is prime.

3, 4, 7, 9, 17, 25, 28, 55, 73, 130, 172, 327, 601, 1201, 2329, 5434, 8807, 14074, 16023

Offset

1,1

Comments

a(20) > 25000. - Michael S. Branicky, Jul 09 2025

Links

Table of n, a(n) for n=1..19.

Crossrefs

Cf. A006882 (double factorials), A076208, A076209, A076210.

Sequence in context: A108796 A364684 A048849 * A167186 A221212 A218278

Adjacent sequences: A076208 A076209 A076210 * A076212 A076213 A076214

Keyword

nonn,more

Author

Zak Seidov, Nov 02 2002

Extensions

a(12)-a(15) (checked k < 5000) from Hugo Pfoertner, Jun 22 2003

a(16)-a(19) from Michael S. Branicky, Jul 09 2025

Status

approved