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A127393
Expansion of k/q^(1/2) in powers of q, where k is the elliptic function defined by sqrt(k) = theta_2/theta_3.
3
4, -16, 56, -160, 404, -944, 2072, -4320, 8648, -16720, 31360, -57312, 102364, -179104, 307672, -519808, 864960, -1419456, 2299832, -3682400, 5831784, -9141808, 14194200, -21842368, 33329700, -50456352, 75813240, -113107872, 167616832, -246811504, 361218392, -525598496
OFFSET
0,1
COMMENTS
The elliptic modulus k is often used in elliptic integrals. - Michael Somos, Jun 11 2017
FORMULA
a(n) = 4*A001938(n).
k = q^(1/2) - 16*q^(3/2) + 56*q^(5/2) - 160*q^(7/2) + ... where the nome q = e^(-Pi*K'/K). - Michael Somos, Jun 11 2017
CROSSREFS
See A001938, the main entry for this sequence, for further information.
Sequence in context: A333282 A212520 A115108 * A239988 A308288 A340257
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Apr 01 2007
STATUS
approved