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%I #9 Jun 20 2021 16:21:42
%S 1,3,1,1,3,7,1,3,1,1,3,5,1,9,1,3,9,1,5,3,5,1,3,1,1,3,1,1,9,11,5,3,5,1,
%T 3,7,1,9,1,9,3,5,1,9,1,3,3,1,1,9,5,5,9,5,3,3,1,1,9,1,5,3,5,1,3,7,1,3,
%U 1,1,3,5,1,15,7,3,3,1,1,9,5,3,15,1,3,3,1,1,21,7,3,9,1,5,3,5,1,3
%N a(n) is the least number k such that k^2+4*n is prime.
%C All terms are odd.
%H Robert Israel, <a href="/A345468/b345468.txt">Table of n, a(n) for n = 1..10000</a>
%e a(5) = 3 because 3^2+4*5 = 29 is prime but 1^2+4*5 and 2^2+4*5 are not.
%p f:= proc(n) local k,m;
%p m:= 4*n;
%p for k from 1 by 2 do
%p if isprime(k^2+m) then return k fi
%p od
%p end proc:
%p map(f, [$1..200]);
%Y Cf. A345469.
%K nonn
%O 1,2
%A _Robert Israel_, Jun 20 2021
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