A249052 - OEIS

%I #10 Jun 26 2022 16:18:02

%S 205,221,305,377,505,545,689,725,745,793,905,1205,1345,1405,1469,1513,

%T 1517,1537,1717,1885,1945,1961,2005,2041,2045,2105,2225,2245,2329,

%U 2353,2525,2533,2669,2701,2845,2993,3005,3205,3305,3497,3505,3737,3757,3805,3893,3965,4069,4105,4145,4205,4321,4369

%N Odd numbers n without prime factors of the form 4k+3 such that x^2-n*y^2=-1 has no solutions.

%C A positive odd integer n is in this sequence iff its squarefree core A007913(n) belongs to A031398. - _Max Alekseyev_, Jun 26 2022

%Y Odd terms of A172001.

%Y Cf. A031398, A031399, A137351.

%K nonn

%O 1,1

%A _Joerg Arndt_, Apr 09 2008