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#25 by Peter Luschny at Mon Sep 04 06:08:21 EDT 2023
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#24 by Michel Marcus at Mon Sep 04 06:01:27 EDT 2023
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#23 by Joerg Arndt at Mon Sep 04 04:38:05 EDT 2023
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#22 by Joerg Arndt at Mon Sep 04 04:38:03 EDT 2023
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| PROG
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(PARI) my(N=70, x='x+O('x^N)); Vec((eta(-x)-1)^7) \\ Joerg Arndt, Sep 04 2023
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| STATUS
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proposed
editing
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#21 by G. C. Greubel at Mon Sep 04 02:44:50 EDT 2023
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#20 by G. C. Greubel at Mon Sep 04 02:44:38 EDT 2023
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| FORMULA
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a(n) = [x^n] ( QPochhammer(-x) - 1 )^7. - G. C. Greubel, Sep 04 2023
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| MATHEMATICA
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Drop[CoefficientList[Series[(QPochhammer[-x] -1)^7, {x, 0, 102}], x], 7] (* G. C. Greubel, Sep 04 2023 *)
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(Magma)
m:=102;
R<x>:=PowerSeriesRing(Integers(), m);
Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^7 )); // G. C. Greubel, Sep 04 2023
(SageMath)
m=100; k=7;
def f(k, x): return (-1 + product( (1+x^j)*(1-x^(2*j))/(1+x^(2*j)) for j in range(1, m+2) ) )^k
def A001485_list(prec):
P.<x> = PowerSeriesRing(QQ, prec)
return P( f(k, x) ).list()
a=A001485_list(m); a[k:] # G. C. Greubel, Sep 04 2023
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| CROSSREFS
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Cf. A001482, A001483, A001484, A001486, A001487, A001488, A047638 - A047649, A047654, A047655, A341243.
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| STATUS
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approved
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#19 by Jon E. Schoenfield at Tue Feb 01 23:38:02 EST 2022
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#18 by Jon E. Schoenfield at Tue Feb 01 23:38:00 EST 2022
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| AUTHOR
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_N. J. A. Sloane_._
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| STATUS
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approved
editing
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#17 by Alois P. Heinz at Sun Feb 07 20:55:01 EST 2021
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#16 by Alois P. Heinz at Sun Feb 07 20:54:58 EST 2021
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| LINKS
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Alois P. Heinz, <a href="/A001485/b001485.txt">Table of n, a(n) for n = 7..10000</a>
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| STATUS
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approved
editing
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