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Number of positive integers <= 2^n of form x^2 + 7 y^2.
0

%I #11 Jan 24 2022 03:57:12

%S 1,1,2,4,7,12,21,39,69,130,240,451,854,1620,3101,5941,11443,22080,

%T 42724,82835,160914,313149,610230,1190802,2326448,4550161,8908095,

%U 17455391,34232368,67184426,131949378,259313689,509925468,1003302084

%N Number of positive integers <= 2^n of form x^2 + 7 y^2.

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

%Y Cf. A020670.

%K nonn

%O 0,3

%A _David W. Wilson_