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A004014 Norms of vectors in the b.c.c. lattice.
(Formerly M2347)
1
0, 3, 4, 8, 11, 12, 16, 19, 20, 24, 27, 32, 35, 36, 40, 43, 44, 48, 51, 52, 56, 59, 64, 67, 68, 72, 75, 76, 80, 83, 84, 88, 91, 96, 99, 100, 104, 107, 108, 115, 116, 120, 123, 128, 131, 132, 136, 139, 140, 144, 147, 148, 152, 155, 160, 163, 164, 168 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Integers such that A004013(n) is nonzero. - Michael Somos, Jul 28 2014

REFERENCES

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 116. (Chapter 4 section 6.7)

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

G. Nebe and N. J. A. Sloane, Home page for this lattice

Index entries for sequences related to b.c.c. lattice

MAPLE

f:= JacobiTheta2(0, z^4)^3+JacobiTheta3(0, z^4)^3:

S:= series(f, z, 1001):

select(t -> coeff(S, z, t) <> 0, [$0..1000]); # Robert Israel, Oct 18 2015

MATHEMATICA

f = EllipticTheta[2, 0, z^4]^3 + EllipticTheta[3, 0, z^4]^3; S = f + O[z]^200; Flatten[Position[CoefficientList[S, z], _?Positive] - 1] (* Jean-Fran├žois Alcover, Oct 23 2016, after Robert Israel *)

CROSSREFS

Cf. A004013.

Sequence in context: A222395 A222269 A047458 * A243177 A113294 A169691

Adjacent sequences:  A004011 A004012 A004013 * A004015 A004016 A004017

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Sean A. Irvine, Oct 17 2015

STATUS

approved

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Last modified February 23 07:28 EST 2018. Contains 299473 sequences. (Running on oeis4.)