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A109146
G.f.: square root of theta series of lattice in A004535.
1
1, 0, 126, 1568, 756, -165312, -1227240, 19894464, 414106686, -456317568, -96106099320, -809737207776, 15047550684488, 345938324437440, -318788546956992, -91256560218798912, -842108390970746508, 15331399952805675648, 380895013380314119302, -178390965727200705696
OFFSET
0,3
LINKS
N. Heninger, E. M. Rains and N. J. A. Sloane, On the Integrality of n-th Roots of Generating Functions, J. Combinatorial Theory, Series A, 113 (2006), 1732-1745.
MATHEMATICA
terms = 20; t2 = EllipticTheta[2, 0, q]; t3 = EllipticTheta[3, 0, q]; s = Sqrt[(t3^7 + 7*t3^3*t2^4)^2 + (t2^7 + 7*t2^3*t3^4)^2] + O[q]^terms // Normal; Join[{1, 0}, Rest[(List @@ s) /. q -> 1]][[1 ;; terms]] (* Jean-François Alcover, Jul 08 2017 *)
CROSSREFS
Sequence in context: A297657 A027805 A027814 * A249197 A249212 A249319
KEYWORD
sign
AUTHOR
STATUS
approved