A061767 - OEIS

A061767

a(n) = smallest composite number of the form k*n + 1.

4, 9, 4, 9, 6, 25, 8, 9, 10, 21, 12, 25, 14, 15, 16, 33, 18, 55, 20, 21, 22, 45, 24, 25, 26, 27, 28, 57, 30, 91, 32, 33, 34, 35, 36, 145, 38, 39, 40, 81, 42, 85, 44, 45, 46, 93, 48, 49, 50, 51, 52, 105, 54, 55, 56, 57, 58, 117, 60, 121, 62, 63, 64, 65, 66, 133, 68, 69, 70

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

a(36) = 145 = 4*36 + 1, since 37, 73 and 109 are primes.

MATHEMATICA

scn[n_]:=Module[{k=1}, While[PrimeQ[k*n+1], k++]; k*n+1]; Array[scn, 70] (* Harvey P. Dale, Jun 20 2014 *)

CROSSREFS

Sequence in context: A089090 A204919 A113484 * A131016 A204996 A061369

Adjacent sequences: A061764 A061765 A061766 * A061768 A061769 A061770