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A152399
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Log of the q-exponential of x, e_q(x,q), evaluated at q=-x.
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1
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1, 1, 4, 9, 16, 22, 29, 49, 94, 156, 221, 318, 521, 883, 1429, 2257, 3605, 5836, 9463, 15264, 24539, 39579, 64148, 103990, 168141, 271623, 439276, 711055, 1150750, 1861287, 3010318, 4870449, 7881944, 12754455, 20635589, 33385764, 54018447
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| The g.f.s for this sequence illustrates the following formula:
log(e_q(x,q)) = Sum_{n>=1} (1-q)^n/(1-q^n)*x^n/n, where
e_q(x,q) = Sum_{n>=0} x^n/faq(n,q) is the q-exponential of x and
faq(n,q) = Product_{k=1..n} (q^k-1)/(q-1) is the q-factorial of n.
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LINKS
| Eric Weisstein, q-Exponential Function from MathWorld.
Eric Weisstein, q-Factorial from MathWorld.
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FORMULA
| L.g.f.: log(e_q(x,-x)) = log(Sum_{n>=0} x^n/[Product_{k=1..n} (1-(-x)^k)/(1+x)]).
L.g.f.: log(e_q(x,-x)) = Sum_{n>=1} x^n*(1+x)^n/(1-(-x)^n)/n.
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EXAMPLE
| L.g.f.: log(e_q(x,-x)) = x + x^2/2 + 4*x^3/3 + 9*x^4/4 + 16*x^5/5 + 22*x^6/6 +...
e_q(x,-x) = 1 + x + x^2 + 2*x^3 + 4*x^4 + 7*x^5 + 11*x^6 + 17*x^7 +... (A152398).
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PROG
| (PARI) a(n)=n*polcoeff(log(sum(k=0, n, x^k/(prod(j=1, k, (1-(-x)^j)/(1+x))+x*O(x^n)))), n)
(PARI) a(n)=polcoeff(sum(k=1, n, x^k*(1+x)^k/(1-(-x)^k)/k)+x*O(x^n), n)
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CROSSREFS
| Cf. A152398 (e_q(x, -x)).
Sequence in context: A155570 A140868 A010460 * A022822 A001639 A162207
Adjacent sequences: A152396 A152397 A152398 * A152400 A152401 A152402
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KEYWORD
| nonn
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AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Dec 16 2008
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