A000286 Number of positive integers <= 2^n of form 2 x^2 + 5 y^2. (Formerly M3251 N1312)

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

0,4

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

Table of n, a(n) for n=0..36.

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

Crossrefs

Sequence in context: A001350 A077238 A185507 * A227620 A036539 A279710

Adjacent sequences: A000283 A000284 A000285 * A000287 A000288 A000289

Keyword

nonn

Author

N. J. A. Sloane

Status

approved