A164775 -id:A164775 - cp's OEIS frontend

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

Felix Fröhlich, Aug 04 2016

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

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

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

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

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

A275650 Number of positive integers k less than 10^n such that k is a sum of two squares and k/2 is an even power.

Original entry on oeis.org

4, 28, 214, 1803, 15830, 142844, 1313047, 12220699, 114790260, 1085885280, 10330026070, 98719755796, 947012920362, 9113815047794, 87950106960771, 850754904051968

Offset: 1

Felix Fröhlich, Aug 04 2016

This sequence gives the values of the counting function V(x), whose values are given in table 3 on page 359 of Shiu, 1986.

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

Cf. A164775: W(x), A275649: U(x).

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

cp's OEIS Frontend

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

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