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A278296
Expansion of ((sqrt(2)-1)*(-sqrt(2);x)_inf - (sqrt(2)+1)*(sqrt(2);x)_inf)/2, where (a;q)_inf is the q-Pochhammer symbol.
3
1, 0, 0, 2, 2, 4, 4, 6, 6, 8, 12, 14, 18, 24, 32, 38, 50, 60, 76, 90, 110, 136, 164, 194, 234, 280, 336, 402, 474, 564, 668, 790, 926, 1096, 1276, 1494, 1754, 2040, 2368, 2758, 3186, 3692, 4268, 4922, 5670, 6528, 7492, 8594, 9858, 11272, 12888, 14722, 16786
OFFSET
0,4
COMMENTS
The q-Pochhammer symbol (a;q)_inf = Product_{k>=0} (1 - a*q^k).
a(n) agrees with A238132(n) for 0 < n < 21.
LINKS
Eric Weisstein's World of Mathematics, q-Pochhammer Symbol.
MAPLE
qP := (x, y) -> (y-1)*QDifferenceEquations:-QPochhammer(-y, x, 99):
dP := x -> (qP(x, sqrt(2)) + qP(x, -sqrt(2)))/2:
simplify(expand(dP(x), x)): seq(coeff(%, x, n), n=0..52); # Peter Luschny, Nov 17 2016
MATHEMATICA
Simplify@(((Sqrt[2] - 1) QPochhammer[-Sqrt[2], x] - (Sqrt[2] + 1) QPochhammer[Sqrt[2], x])/2 + O[x]^53)[[3]]
CROSSREFS
Cf. A238132.
Sequence in context: A005186 A259881 A238132 * A332305 A340282 A008642
KEYWORD
nonn
AUTHOR
STATUS
approved