A089726 Smallest prime of the form nk+1, k > n.

3, 7, 13, 29, 31, 43, 71, 73, 109, 131, 199, 157, 313, 211, 241, 337, 307, 379, 419, 421, 463, 617, 599, 601, 701, 859, 757, 953, 929, 991, 1117, 1153, 1123, 1259, 1471, 1549, 1481, 1483, 1873, 1721, 1723, 1933, 1979, 2069, 2161, 2347, 2351, 2593, 2549, 2551

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

a(7)=71 because 7*10+1=71 is prime, whereas 7*8+1=57 and 7*9+1=64 are composite.

Mathematica

f[n_] := Block[{k = n + 1}, While[ !PrimeQ[k*n + 1], k++ ]; k*n + 1]; Array[f, 50] (* Robert G. Wilson v, Dec 17 2009 *)

Crossrefs

Cf. A089727.

Sequence in context: A146904 A146432 A258349 * A093575 A080166 A116872

Adjacent sequences: A089723 A089724 A089725 * A089727 A089728 A089729

Keyword

nonn,easy

Author

Amarnath Murthy, Nov 18 2003

Extensions

More terms from Hugo Pfoertner, Apr 01 2004

Status

approved