A281295 - OEIS

%I #6 Sep 08 2022 08:46:18

%S 2,3,5,7,11,13,17,19,23,29,31,37,41,43,59,61,67,71,73,79,83,89,97,101,

%T 107,109,113,127,131,137,139,149,151,157,167,173,179,181,191,193,197,

%U 211,223,227,229,233,239,241,251,263,271,277,281,283,293,307,313,317

%N Primes which cannot be written as x^2 + 11*y^2, where x, y > 0.

%C  Integers n that cannot be expressed as the product of two numbers of the form a + b*sqrt(-11), where a > 0 and b >= 0 (excluding 1 and n).

%F a(n) ~ 6/5 * n log n.

%o (Magma) Sort([11] cat [p: p in PrimesUpTo(317) | NormEquation(11, p) eq false]);

%Y Cf. A033209.

%K nonn

%O 1,1

%A _Arkadiusz Wesolowski_, Jan 19 2017