A275649 - OEIS

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

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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