A243450 Primes of the form n^2 + 15.

19, 31, 79, 211, 271, 499, 691, 1039, 1171, 1459, 1951, 2131, 2719, 4111, 4639, 5791, 7411, 7759, 9619, 10831, 11251, 15391, 17971, 24979, 29599, 31699, 33871, 38431, 40819, 42451, 44959, 55711, 56659, 58579, 61519, 65551, 68659, 73999, 80671, 87631, 88819

Offset: 1

Author

Vincenzo Librandi, Jun 05 2014

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A121982 (associated n).

Cf. similar sequences listed in A243449.

Programs

Magma

[a: n in [0..1000] | IsPrime(a) where a is n^2+15];

Mathematica

Select[Table[n^2 + 15, {n, 0, 1000}], PrimeQ]

PARI

list(lim)=my(v=List(),t); forstep(k=2,sqrtint(lim\1-15),2, if(isprime(t=k^2+15), listput(v,t))); Vec(v) \\ Charles R Greathouse IV, Nov 06 2024

Formula

a(n) >> n^2 log n. - Charles R Greathouse IV, Nov 06 2024