cp's OEIS Frontend

A319228 Number of primes of the form b^2 + b + 1 for b <= 10^n.

%I A319228 #26 Sep 18 2018 12:14:52
%S A319228 6,32,189,1410,10751,88118,745582,6456835,56988601,510007598,
%T A319228 4615215645
%N A319228 Number of primes of the form b^2 + b + 1 for b <= 10^n.
%e A319228 a(1) = 6 because there are 6 primes of the form b^2 + b + 1 for b <= 10: 3, 7, 13, 31, 43 and 73.
%o A319228 (PARI) {a(n) = sum(k=0, 10^n, isprime(k^2+k+1))}
%o A319228 (Python)
%o A319228 from sympy import isprime
%o A319228 def A319228(n):
%o A319228     c, b, b2, n10 = 0, 1, 3, 10**n
%o A319228     while b <= n10:
%o A319228         if isprime(b2):
%o A319228             c += 1
%o A319228         b += 1
%o A319228         b2 += 2*b
%o A319228     return c # _Chai Wah Wu_, Sep 17 2018
%Y A319228 Cf. A002383, A002384, A206709.
%K A319228 nonn,more
%O A319228 1,1
%A A319228 _Seiichi Manyama_, Sep 14 2018
%E A319228 a(10) from _Chai Wah Wu_, Sep 17 2018
%E A319228 a(11) from _Chai Wah Wu_, Sep 18 2018