A087572 Smallest prime of the form n + (n-1) + (n-2) + ...(n-k), k < n, or 0 if no such prime exists.

0, 2, 3, 7, 5, 11, 7, 0, 17, 19, 11, 23, 13, 0, 29, 31, 17, 0, 19, 0, 41, 43, 23, 47, 0, 0, 53, 0, 29, 59, 31, 0, 0, 67, 0, 71, 37, 0, 0, 79, 41, 83, 43, 0, 89, 0, 47, 0, 97, 0, 101, 103, 53, 107, 109, 0, 113, 0, 59, 0, 61, 0, 0, 127, 0, 131, 67, 0, 137, 139, 71, 0, 73, 0, 149, 151, 0

Offset: 1

Author

Amarnath Murthy, Sep 17 2003

Keywords

• nonn

Comments

Trivially a(n) = 0 if n and 2n-1 both are composite. i.e. (k = 0 or 1.)

If a(n) > 0 then a(n) = A034694(n-1). - David Wasserman, Jun 07 2005

Extensions

More terms from David Wasserman, Jun 07 2005