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A330318
a(n) = Sum_{i=0..n} r(i)*r(i+1)/4, where r(n) = A004018(n) is the number of ways of writing n as a sum of two squares.
3
1, 5, 5, 5, 13, 13, 13, 13, 17, 25, 25, 25, 25, 25, 25, 25, 33, 41, 41, 41, 41, 41, 41, 41, 41, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 73, 73, 73, 73, 89, 89, 89, 89, 89, 89, 89, 89, 89, 101, 101, 101, 117, 117, 117, 117, 117, 117, 117, 117, 117, 117
OFFSET
0,2
REFERENCES
H. Iwaniec. Spectral methods of automorphic forms, volume 53 of Graduate Studies in Mathematics. American Mathematical Society, Providence, RI, 2002.
LINKS
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
Partial sums of A330316.
Sequence in context: A265821 A266953 A224165 * A334934 A131286 A183390
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 11 2019
STATUS
approved