A330317 a(n) = Sum_{i=0..n} r(i)*r(i+1), where r(n) = A004018(n) is the number of ways of writing n as a sum of two squares.

4, 20, 20, 20, 52, 52, 52, 52, 68, 100, 100, 100, 100, 100, 100, 100, 132, 164, 164, 164, 164, 164, 164, 164, 164, 260, 260, 260, 260, 260, 260, 260, 260, 260, 260, 260, 292, 292, 292, 292, 356, 356, 356, 356, 356, 356, 356, 356, 356, 404, 404, 404, 468, 468, 468, 468, 468, 468, 468, 468, 468, 468, 468, 468, 532, 532, 532

Offset

0,1

References

H. Iwaniec. Spectral methods of automorphic forms, volume 53 of Graduate Studies in Mathematics. American Mathematical Society, Providence, RI, 2002.

Links

Table of n, a(n) for n=0..66.

Fernando Chamizo, Correlated sums of r(n), J. Math. Soc. Japan, 51(1):237-252, 1999.

Fernando Chamizo, and Roberto J. Miatello, Sums of squares in real quadratic fields and Hilbert modular groups, arXiv preprint arXiv:1812.10725 [math.NT], 2018.

Crossrefs

Cf. A004018, A330316, A330318.

Partial sums of A330315.

Sequence in context: A131745 A261755 A288319 * A151727 A146568 A087326

Adjacent sequences: A330314 A330315 A330316 * A330318 A330319 A330320

Keyword

nonn,changed

Author

N. J. A. Sloane, Dec 11 2019

Status

approved