A000286 Number of positive integers <= 2^n of form 2 x^2 + 5 y^2.

0, 1, 1, 4, 5, 11, 20, 36, 65, 119, 218, 412, 770, 1466, 2784, 5322, 10226, 19691, 38048, 73665, 142927, 277822, 540851, 1054502, 2058507, 4023164, 7871226, 15414517, 30213010, 59266164, 116343183, 228545303, 449240025, 883569304, 1738768584, 3423466797, 6743729031

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

References

• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• D. Shanks and L. P. Schmid, Variations on a theorem of Landau. Part I, Math. Comp., 20 (1966), 551-569.
• Index entries for sequences related to populations of quadratic forms