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%I #13 Jul 20 2022 08:49:20
%S 5,229,401,577,1129,1297,8101,11321,11257,18229,7057,23593,27689,8761,
%T 56857,146077,63361,25601,24337,55441,439573,14401,32401,78401,70969,
%U 69697,376897,106537,41617,160001,193601,57601,197137,367721,414433,1432813,444089,331777
%N Smallest p == 1 (mod 4) such that Q(sqrt(p)) has class number 2n+1.
%C Also smallest odd prime p such that Q(sqrt(p)) has narrow class number (also called form class number) 2n+1.
%C Conjecture: a(n) > A002148(n) for all n.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Class_number_(number_theory)#Class_numbers_of_quadratic_fields">Class numbers of quadratic fields</a>
%H <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a>
%F a(n) = min(A355876(n),A355877(n)).
%e p = 229 is the smallest odd prime such that Q(sqrt(p)) has class number 3, so a(1) = 229.
%o (PARI) a(n) = forprime(p=2, oo, if(p%4==1 && qfbclassno(p)==2*n+1, return(p)))
%Y Cf. A355876, A355877.
%K nonn
%O 0,1
%A _Jianing Song_, Jul 20 2022
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