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A076180
Indices of spheres mentioned in A071609.
0
1, 2, 5, 8, 13, 23, 35, 63, 76, 86, 123, 163, 226, 264, 287, 374, 514, 523, 576, 664, 715, 787, 924, 927, 963, 1074, 1137, 1364, 1487, 1576, 1786, 2176, 2475, 2614, 2837, 2877, 2925, 3536, 3576, 4025, 4487, 4638, 5215, 6026, 6527, 6726, 6774
OFFSET
1,2
REFERENCES
J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, Table 4.3, p. 107.
FORMULA
a(n) = k for which A000378(k) = A071609(n)
EXAMPLE
a(7)=35 because A000378(35)=A071609(7)=41
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Nov 01 2002
STATUS
approved