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Number of positive integers <= 2^n of the form x^2 + 5*y^2.
0

%I #14 Jan 24 2022 03:56:14

%S 1,1,2,4,7,13,22,40,73,132,245,458,864,1638,3123,5979,11484,22140,

%T 42773,82865,160809,312659,608857,1187323,2318344,4531879,8867913,

%U 17369053,34048772,66799240,131146379,257651913,506503984,996288321

%N Number of positive integers <= 2^n of the form x^2 + 5*y^2.

%H <a href="/index/Qua#quadpop">Index entries for sequences related to populations of quadratic forms</a>

%Y Cf. A020669.

%K nonn

%O 0,3

%A _David W. Wilson_