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%I #14 Mar 24 2020 06:39:59
%S 1,102091236,732722,6181,314,1,199,3,2,128,1,5,2,1,4,7,5,1,4,3,1,6,1,
%T 2,9,4,2,1,6,8,1,9,7,1,3,1,4,2,1,6,2,1,8,4,1,11,11,3,7,1,6,6,2,15,1,3,
%U 2,1,12,1,15,1,3,4,1,14,1,2,5,3,2,1,10,16,1,13,1,8,1
%N a(n) is the index in primes of A306499(n), or 0 if A306499(n) = 0.
%C a(n) is the smallest integer k such that Sum_{i=1..k} Kronecker(A003658(n),prime(i)) > 0, or 0 if no such k exists.
%C See A306499 for the actual primes.
%e See A306499 for the example that shows a(16) = 7.
%o (PARI) b(n) = my(i=0); forprime(p=2, oo, i+=kronecker(n, p); if(i>0, return(p)))
%o for(n=1, 300, if(isfundamental(n), print1(primepi(b(n)), ", ")))
%o (Sage) # uses[KroneckerSum from A306499]
%o A306499 = KroneckerSum()
%o print([prime_pi(next(A306499)) for _ in range(77)]) # _Peter Luschny_, Feb 26 2019
%Y Cf. A003658, A306499, A306503.
%K nonn
%O 1,2
%A _Jianing Song_, Feb 19 2019
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