A323353 - OEIS

%I #11 Jan 13 2019 03:24:41

%S 2,3,7,11,13,73,401,421,677,3673,4903,13147,24547

%N Numbers k such that A015525(k) is prime.

%o (PARI) print1(2,", ");anm2=1;anm1=3;for(n=3,1000,an=3*anm1+8*anm2;anm2=anm1;anm1=an;if(isprime(an),print1(n,", ")))

%o (Perl) use ntheory ":all"; sub isok { is_prob_prime(lucasu(3, -8, $_[0])) }; for (1..700) { print "$_\n" if isok($_) }; # _Daniel Suteu_, Jan 12 2019

%Y Cf. A015525, A323354.

%K nonn,more,hard

%O 1,1

%A _Hugo Pfoertner_, Jan 12 2019

%E a(13) from _Daniel Suteu_, Jan 12 2019