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A008452 Number of ways of writing n as a sum of 9 squares. 5
1, 18, 144, 672, 2034, 4320, 7392, 12672, 22608, 34802, 44640, 60768, 93984, 125280, 141120, 182400, 262386, 317376, 343536, 421344, 557280, 665280, 703584, 800640, 1068384, 1256562, 1234080, 1421184, 1851264, 2034720, 2057280, 2338560 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

E. Grosswald, Representations of Integers as Sums of Squares. Springer-Verlag, NY, 1985, p. 121.

G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 314.

LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000

Shi-Chao Chen, Congruences for rs(n), Journal of Number Theory, Volume 130, Issue 9, September 2010, Pages 2028-2032.

S. C. Milne, Infinite families of exact sums of squares formulas, Jacobi elliptic functions, continued fractions and Schur functions, Ramanujan J., 6 (2002), 7-149.

M. Peters, Sums of nine squares, Acta Arith., 102 (2002), 131-135.

Index entries for sequences related to sums of squares

FORMULA

G.f.: theta_3(0,q)^9, where theta_3 is the 3rd Jacobi theta function. - Ilya Gutkovskiy, Jan 13 2017

a(n) = (18/n)*Sum_{k=1..n} A186690(k)*a(n-k), a(0) = 1. - Seiichi Manyama, May 27 2017

MAPLE

(sum(x^(m^2), m=-10..10))^9;

MATHEMATICA

Table[SquaresR[9, n], {n, 0, 32}] (* Ray Chandler, Nov 28 2006 *)

PROG

(Sage)

Q = DiagonalQuadraticForm(ZZ, [1]*9)

Q.representation_number_list(37) # Peter Luschny, Jun 20 2014

CROSSREFS

9th column of A286815. - Seiichi Manyama, May 27 2017

Cf. A008431.

Sequence in context: A232820 A143992 A127408 * A126900 A178759 A036397

Adjacent sequences:  A008449 A008450 A008451 * A008453 A008454 A008455

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

Extended by Ray Chandler, Nov 28 2006

STATUS

approved

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Last modified July 27 20:56 EDT 2017. Contains 289866 sequences.