OFFSET
0,4
COMMENTS
a(n) > 0 iff n is in A047470. - Robert Israel, Jul 06 2016
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Robert Israel, Table of n, a(n) for n = 0..10000
J. H. Conway and N. J. A. Sloane, Sphere Packings, Lattices and Groups, Springer-Verlag, p. 120.
G. L. Hall, Comment on the paper "Theta series and magic numbers for diamond and certain ionic crystal structures" [J. Math. Phys. 28, 1653 (1987)]. Journal of Mathematical Physics; Sep. 1988, Vol. 29 Issue 9, pp. 2090-2092. - From N. J. A. Sloane, Dec 18 2012
N. J. A. Sloane, Theta series and magic numbers for diamond and certain ionic crystal structures, J. Math. Phys. 28 (1987), 1653-1657.
FORMULA
(theta_2^3 + theta_3^3 + theta_4^3) / 2.
MAPLE
S:= series((JacobiTheta2(0, z^4)^3 + JacobiTheta3(0, z^4)^3 + JacobiTheta4(0, z^4)^3)/2, z, 101):
seq(coeff(S, z, j), j=0..100); # Robert Israel, Jul 06 2016
MATHEMATICA
terms = 68; s = Simplify[Normal[(EllipticTheta[2, 0, z^4]^3 + EllipticTheta[3, 0, z^4]^3 + EllipticTheta[4, 0, z^4]^3)/2 + O[z]^terms], z > 0]; CoefficientList[s, z] (* Jean-François Alcover, Jul 07 2017 *)
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
STATUS
approved