A053185 Primes of the form p^2 + p - 1 when p is prime.

5, 11, 29, 131, 181, 379, 991, 1721, 2861, 3539, 6971, 8009, 10301, 10711, 17291, 22349, 26731, 32941, 36671, 37441, 39799, 54521, 58321, 69431, 79241, 109891, 122149, 139501, 161201, 175979, 186191, 187921, 202049, 212981, 214831, 249499

Offset: 1

Author

Enoch Haga, Mar 01 2000

Keywords

• easy
• nonn

Comments

Previous name: Primes produced in A053184.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1200

Crossrefs

Cf. A053184.

Programs

Magma

[p: p in PrimesUpTo(600) | IsPrime(p) where p is p^2+p-1]; // Vincenzo Librandi, Aug 12 2017

Mathematica

Select[#^2 + # - 1 &/@Prime[Range[200]], PrimeQ] (* Vincenzo Librandi, Aug 12 2017 *)

PARI

isA053185(n)={local(r);r=0;for(i=floor(sqrt(n+1)),ceil(sqrt(n)-1),if(isprime(i) && n==i^2+i-1 && isprime(n),r=1));r} \\ Michael B. Porter, May 10 2010

PARI

lista(nn) = forprime(p=2, nn, if (isprime(q=p^2+p-1), print1(q, ", "))); \\ Michel Marcus, Aug 12 2017

Extensions

New name from Michel Marcus, Aug 12 2017