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A000605 Number of points of norm <= n in cubic lattice.
(Formerly M4406 N1860)
7
1, 7, 33, 123, 257, 515, 925, 1419, 2109, 3071, 4169, 5575, 7153, 9171, 11513, 14147, 17077, 20479, 24405, 28671, 33401, 38911, 44473, 50883, 57777, 65267, 73525, 82519, 91965, 101943, 113081, 124487, 137065, 150555, 164517, 179579, 195269, 212095 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 107.

W. Fraser and C. C. Gotlieb, A calculation of the number of lattice points in the circle and sphere, Math. Comp., 16 (1962), 282-290.

H. Gupta, A Table of Values of N_3(t), Proc. National Institute of Sciences of India, 13 (1947), 35-63.

Z. C. Holden, R. M. Richard, J. M. Herbert, Periodic boundary conditions for QM/MM calculations: Ewald summation for extended Gaussian basis sets, The Journal of Chemical Physics, J. Chem. Phys. 139, 244108 (2013); http://dx.doi.org/10.1063/1.4850655

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n=0..500

FORMULA

a(n) = A117609(n^2). - R. J. Mathar, Apr 21 2010

MATHEMATICA

Table[Sum[SquaresR[3, k], {k, 0, n^2}], {n, 0, 37}]

PROG

(C)

int A000605(int i)

{

    const int ring = i*i;

    int result = 0;

    for (int a = -i; a <= i; a++)

        for (int b = -i; b <= i; b++)

            for (int c = -i; c <= i; c++)

                if ( ring >= a*a+b*b+c*c )  result++;

    return result;

} /* Oskar Wieland, Apr 08 2013 */

(PARI)

N=66;  q='q+O('q^(N^2));

t=Vec((eta(q^2)^5/(eta(q)^2*eta(q^4)^2))^3/(1-q));  /* A117609 */

vector(sqrtint(#t), n, t[(n-1)^2+1])

/* Joerg Arndt, Apr 08 2013 */

CROSSREFS

Cf. A117609 (number of lattice points inside the ball x^2+y^2+z^2 <= n).

Sequence in context: A100855 A256860 A221036 * A215054 A114014 A229515

Adjacent sequences:  A000602 A000603 A000604 * A000606 A000607 A000608

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from David W. Wilson, May 22 2000

STATUS

approved

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Last modified March 29 13:14 EDT 2017. Contains 284270 sequences.