%I #8 Jan 25 2022 21:49:34
%S 1,1,2,2,6,10,19,32,58,105,194,364,682,1295,2467,4723,9059,17448,
%T 33706,65256,126643,246179,479336,934603,1824646,3566467,6978040,
%U 13666391,26788334,52551600,103168475,202676349,398411711,783639902,1542192977
%N Number of positive integers <= 2^n of form x^2 + 13 y^2.
%Y Cf. A247881.
%K nonn
%O 0,3
%A _David W. Wilson_