A275649 Number of squarefree odd numbers k > 1 less than 10^n such that k is a sum of two squares.

2, 14, 112, 997, 8982, 82305, 764092, 7159654, 67581778, 641696858, 6122456540, 58649349611, 563729377405, 5434188304040, 52515178669973, 508607849995010

Offset

1,1

Comments

This sequence gives the values of the counting function U(x), whose values are given in table 2 on page 359 of Shiu, 1986.

Links

Table of n, a(n) for n=1..16.

P. Shiu, Counting sums of two squares: the Meissel-Lehmer method, Mathematics of Computation, 47 (1986), 351-360.

Mathematica

Table[Count[Range[1, 10^n, 2], k_ /; SquareFreeQ@ k && SquaresR[2, k] > 0], {n, 6}] (* Michael De Vlieger, Aug 04 2016 *)

Crossrefs

Cf. A164775: W(x), A275650: V(x).

Sequence in context: A359108 A214766 A330553 * A199649 A357584 A216581

Adjacent sequences: A275646 A275647 A275648 * A275650 A275651 A275652

Keyword

nonn,more

Author

Felix Fröhlich, Aug 04 2016

Extensions

a(7), a(11) and a(12) corrected and a(13)-a(16) added by Hiroaki Yamanouchi, Dec 25 2016

Status

approved