A108151 a(n) = n^2 + 3*n + 1 if prime or 0 if composite.

5, 11, 19, 29, 41, 0, 71, 89, 109, 131, 0, 181, 0, 239, 271, 0, 0, 379, 419, 461, 0, 0, 599, 0, 701, 0, 811, 0, 929, 991, 0, 0, 0, 1259, 0, 0, 1481, 1559, 0, 1721, 0, 0, 1979, 2069, 2161, 0, 2351, 0, 2549, 0

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Example

1^2+3*1+1 = 5 prime so a(1) = 5.
2^2+3*2+1 = 11 prime so a(2) = 11.
6^2+3*6+1 = 55 = 5*11 composite so a(6) = 0.

Mathematica

Table[t=n^2+3n+1; If[PrimeQ[t], t, 0], {n, 50}] (* James C. McMahon, Feb 21 2024 *)

Crossrefs

Cf. A028387.

Sequence in context: A239732 A130828 A244241 * A209188 A356247 A215886

Adjacent sequences: A108148 A108149 A108150 * A108152 A108153 A108154

Keyword

nonn,less

Author

Pierre CAMI, Jun 06 2005

Status

approved