Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #14 Sep 08 2022 08:45:00
%S 5,11,29,131,181,379,991,1721,2861,3539,6971,8009,10301,10711,17291,
%T 22349,26731,32941,36671,37441,39799,54521,58321,69431,79241,109891,
%U 122149,139501,161201,175979,186191,187921,202049,212981,214831,249499
%N Primes of the form p^2 + p - 1 when p is prime.
%C Previous name: Primes produced in A053184.
%H Vincenzo Librandi, <a href="/A053185/b053185.txt">Table of n, a(n) for n = 1..1200</a>
%t Select[#^2 + # - 1 &/@Prime[Range[200]], PrimeQ] (* _Vincenzo Librandi_, Aug 12 2017 *)
%o (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
%o (PARI) lista(nn) = forprime(p=2, nn, if (isprime(q=p^2+p-1), print1(q, ", "))); \\ _Michel Marcus_, Aug 12 2017
%o (Magma) [p: p in PrimesUpTo(600) | IsPrime(p) where p is p^2+p-1]; // _Vincenzo Librandi_, Aug 12 2017
%Y Cf. A053184.
%K easy,nonn
%O 1,1
%A _Enoch Haga_, Mar 01 2000
%E New name from _Michel Marcus_, Aug 12 2017