cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 16 results. Next

A001488 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^10 in powers of x.

Original entry on oeis.org

1, -10, 45, -120, 200, -162, -160, 810, -1530, 1730, -749, -1630, 4755, -7070, 6700, -2450, -5295, 14070, -20010, 19350, -10157, -6290, 25515, -40660, 44940, -34268, 9180, 24510, -57195, 78060, -79087, 56610, -13935, -39600, 89805, -121638, 125405
Offset: 10

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Keywords

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    m:=102;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^10 )); // G. C. Greubel, Sep 04 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 10):
    seq(a(n), n=10..46);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=46; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] -1)^10, {x,0,nmax}], x]//Drop[#,10] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    Drop[CoefficientList[Series[(QPochhammer[-x] -1)^10, {x,0,102}], x],10] (* G. C. Greubel, Sep 04 2023 *)
  • PARI
    my(N=55,x='x+O('x^N)); Vec((eta(-x)-1)^10) \\ Joerg Arndt, Sep 05 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=100; k=10;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A001488_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A001488_list(m); a[k:] # G. C. Greubel, Sep 04 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^10. - G. C. Greubel, Sep 04 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047654 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^2 in powers of x.

Original entry on oeis.org

1, -2, 1, 0, -2, 2, -2, 2, 1, 0, 2, -2, 3, 0, 2, 0, 0, 2, -2, 0, -2, 2, -1, 0, 0, -2, -2, -2, 1, -2, 0, -2, -2, 0, 2, 0, -2, 0, -2, 0, 0, 0, 1, 2, 0, 0, 2, 0, 2, 0, 1, 2, 0, -2, 2, 2, 0, 2, 0, 2, 0, 2, 2, 0, -4, 0, 0, 2, 1, -2, 0, -2, 0, 0, 0, 0, 2, -4, 1, 0, 0, -2, -2, -2, -2, 0, 0, -2, 0, 2, -2, 2, -2
Offset: 2

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=120;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^2 )); // G. C. Greubel, Sep 07 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 2):
    seq(a(n), n=2..94);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=94; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] - 1)^2, {x, 0, nmax}], x]//Drop[#, 2] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=2}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 125}], x], k]] (* G. C. Greubel, Sep 07 2023 *)
  • PARI
    seq(n)={Vec((prod(j=1, n, 1-(-x)^j + O(x^n)) - 1)^2)} \\ Andrew Howroyd, Feb 07 2021
    
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=125; k=2;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047654_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047654_list(m); a[k:] # G. C. Greubel, Sep 07 2023

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^2. - G. C. Greubel, Sep 07 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047655 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^3 in powers of x.

Original entry on oeis.org

1, -3, 3, -1, -3, 6, -6, 6, 0, -3, 6, -9, 8, -6, 0, 0, -6, 6, -13, 3, -6, 3, 0, -3, 6, -9, 6, -3, 6, 0, 6, 6, -3, 11, 0, 6, 0, 9, 0, 0, 0, -3, 13, 0, 0, -6, 0, -6, 3, -3, -6, 0, -15, -6, -3, 0, -6, 0, -6, 0, -6, -6, 0, -11, 0, 0, -6, 0, 6, 0, 6, 0, 0, 0, -3, 19, 12, -3, 0, 0, 6, 6, 6, 6, 0, 0, 6, 0, 21, 3
Offset: 3

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=120;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^3 )); // G. C. Greubel, Sep 07 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 3):
    seq(a(n), n=3..92);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=92; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] - 1)^3, {x,0,nmax}], x]//Drop[#, 3] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=3}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 125}], x], k]] (* G. C. Greubel, Sep 07 2023 *)
  • PARI
    my(x='x+O('x^99)); Vec((eta(-x)-1)^3) \\ Joerg Arndt, Sep 07 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=125; k=3;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047655_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047655_list(m); a[k:] # G. C. Greubel, Sep 07 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^3. - G. C. Greubel, Sep 07 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047649 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^11 in powers of x.

Original entry on oeis.org

1, -11, 55, -165, 319, -352, -44, 1100, -2585, 3542, -2519, -1530, 8085, -14410, 16170, -9460, -6644, 28105, -46145, 50248, -32802, -6193, 57200, -102575, 121968, -100397, 35123, 60390, -158840, 226413, -234344, 168773, -37070, -131175, 290851, -391402
Offset: 11

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=75;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^(11) )); // G. C. Greubel, Sep 05 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 11):
    seq(a(n), n=11..46);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=46; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] - 1)^11, {x,0,nmax}], x]//Drop[#, 11] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=11}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 75}], x], k]] (* G. C. Greubel, Sep 05 2023 *)
  • PARI
    my(N=55,x='x+O('x^N)); Vec((eta(-x)-1)^11) \\ Joerg Arndt, Sep 05 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=75; k=11;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047649_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047649_list(m); a[k:] # G. C. Greubel, Sep 05 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^11. - G. C. Greubel, Sep 05 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047638 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^13 in powers of x.

Original entry on oeis.org

1, -13, 78, -286, 702, -1131, 845, 1300, -5928, 11583, -13715, 5915, 15834, -47477, 73658, -71201, 20436, 79391, -198796, 280345, -258557, 92807, 200850, -536341, 773916, -768222, 432705, 204477, -979628, 1626196, -1856569, 1471184, -452192
Offset: 13

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=80;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^(13) )); // G. C. Greubel, Sep 07 2023
    
  • Maple
    N:= 100: # to get a(13)..a(N)
    G:= (mul(1-(-x)^j,j=1..N)-1)^13:
    S:= series(G,x,N+1):
    seq(coeff(S,x,n),n=13..N); # Robert Israel, Aug 08 2018
  • Mathematica
    With[{k=13}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 75}], x], k]] (* G. C. Greubel, Sep 07 2023 *)
  • PARI
    my(x='x+O('x^40)); Vec((eta(-x)-1)^13) \\ Joerg Arndt, Sep 07 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=75; k=13;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047638_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047638_list(m); a[k:] # G. C. Greubel, Sep 07 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^13. - G. C. Greubel, Sep 07 2023

Extensions

Definition corrected by Robert Israel, Aug 08 2018

A047265 Triangle T(n,k), for n >= 1, 1 <= k <= n, read by rows, giving coefficient of x^n in expansion of (Product_{j>=1} (1-(-x)^j) - 1 )^k.

Original entry on oeis.org

1, -1, 1, 0, -2, 1, 0, 1, -3, 1, -1, 0, 3, -4, 1, 0, -2, -1, 6, -5, 1, -1, 2, -3, -4, 10, -6, 1, 0, -2, 6, -3, -10, 15, -7, 1, 0, 2, -6, 12, 0, -20, 21, -8, 1, 0, 1, 6, -16, 19, 9, -35, 28, -9, 1, 0, 0, 0, 16, -35, 24, 28, -56, 36, -10, 1, -1, 2, -3, -6, 40, -65, 21, 62, -84, 45, -11, 1
Offset: 1

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Keywords

Comments

This is an ordinary convolution triangle. If a column k=0 starting at n=0 is added, then this is the Riordan triangle R(1, f(x)), with
f(x) = Product_{j>=1} (1 - (-x)^j) - 1, generating {0, {A121373(n)}{n>=1}}. - _Wolfdieter Lang, Feb 16 2021

Examples

			Triangle starts:
   1,
  -1,   1,
   0,  -2,   1,
   0,   1,  -3,   1,
  -1,   0,   3,  -4,   1,
   0,  -2,  -1,   6,  -5,   1,
  -1,   2,  -3,  -4,  10,  -6,   1,
   0,  -2,   6,  -3, -10,  15,  -7,   1,
   0,   2,  -6,  12,   0, -20,  21,  -8,   1,
   0,   1,   6, -16,  19,   9, -35,  28,  -9,   1,
   0,   0,   0,  16, -35,  24,  28, -56,  36, -10,   1,
  -1,   2,  -3,  -6,  40, ...
		

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 40);
    T:= func< n,k | Coefficient(R!( (-1)^n*(-1 + (&*[1 - x^j: j in [1..n]]) )^k ), n) >;
    [T(n,k): k in [1..n], n in [1..12]]; // G. C. Greubel, Sep 07 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    T:= proc(n, k) option remember;
         `if`(k=0, `if`(n=0, 1, 0), `if`(k=1, `if`(n=0, 0, g(n)),
             (q-> add(T(j, q)*T(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    seq(seq(T(n, k), k=1..n), n=1..12);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    T[n_, k_]:= SeriesCoefficient[(-1)^n*(Product[(1-x^j), {j,n}] - 1)^k, {x, 0, n}];
    Table[T[n, k], {n,12}, {k,n}]//Flatten (* Jean-François Alcover, Dec 05 2013 *)
  • PARI
    T(n,k) = polcoeff((-1)^n*(Ser(prod(i=1,n,1-x^i)-1)^k), n) \\ Ralf Stephan, Dec 08 2013
    
  • SageMath
    from sage.combinat.q_analogues import q_pochhammer
    P. = PowerSeriesRing(ZZ, 50)
    def T(n,k): return P( (-1)^n*(-1 + q_pochhammer(n,x,x) )^k ).list()[n]
    flatten([[T(n,k) for k in range(1,n+1)] for n in range(1,13)]) # G. C. Greubel, Sep 07 2023

Formula

G.f. column k: (Product_{j>=1} (1 - (-x)^j) - 1)^k, for k >= 1. See the name and a Riordan triangle comment above. - Wolfdieter Lang, Feb 16 2021
From G. C. Greubel, Sep 07 2023: (Start)
T(n, n) = 1.
T(n, n-1) = -A000027(n-1).
T(n, n-2) = A000217(n-3).
T(n, n-3) = -A000292(n-5).
Sum_{k=1..n} T(n, k) = (-1)^n * A307059(n).
Sum_{k=1..n} (-1)^k * T(n, k) = (-1)^n * A000041(n). (End)

A047645 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^20 in powers of x.

Original entry on oeis.org

1, -20, 190, -1140, 4825, -15124, 35320, -57760, 45220, 80560, -405954, 910460, -1289340, 852340, 1259530, -5357924, 10151510, -12048660, 5883350, 12186960, -40135713, 66244280, -69648870, 28191460, 66920755, -195366168, 300881530
Offset: 20

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=80;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^(20) )); // G. C. Greubel, Sep 06 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 20):
    seq(a(n), n=20..46);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=46; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] -1)^20, {x,0,nmax}], x]//Drop[#, 20] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=20}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 75}], x], k]] (* G. C. Greubel, Sep 06 2023 *)
  • PARI
    my(N=44, x='x+O('x^N)); Vec((eta(-x)-1)^20) \\ Joerg Arndt, Sep 06 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=75; k=20;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047645_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047645_list(m); a[k:] # G. C. Greubel, Sep 06 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^20. - G. C. Greubel, Sep 06 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047648 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^23 in powers of x.

Original entry on oeis.org

1, -23, 253, -1771, 8832, -33143, 95611, -209231, 317009, -181401, -686642, 2828977, -6099278, 8422623, -4906406, -10919687, 41968146, -78977952, 93297545, -40351223, -117265247, 367581446, -606562624, 631382751, -207879980, -777907725, 2132043121
Offset: 23

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=75;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^(23) )); // G. C. Greubel, Sep 05 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 23):
    seq(a(n), n=23..49);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=49; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] -1)^23, {x,0,nmax}], x]//Drop[#, 23] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=23}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 75}], x], k]] (* G. C. Greubel, Sep 05 2023 *)
  • PARI
    my(N=44, x='x+O('x^N)); Vec((eta(-x)-1)^23) \\ Joerg Arndt, Sep 05 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=75; k=23;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047648_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047648_list(m); a[k:] # G. C. Greubel, Sep 05 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^23. - G. C. Greubel, Sep 05 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047639 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^14 in powers of x.

Original entry on oeis.org

1, -14, 91, -364, 987, -1820, 1897, 754, -8008, 18928, -26845, 19460, 15015, -76272, 141065, -163072, 90727, 99386, -368277, 602616, -643734, 358190, 274547, -1101100, 1801086, -1982330, 1344525, 148316, -2163590, 4032756, -4938843, 4216576
Offset: 14

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Author

Keywords

Crossrefs

Programs

  • Magma
    m:=80;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^(14) )); // G. C. Greubel, Sep 07 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 14):
    seq(a(n), n=14..45);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=45; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] - 1)^14, {x,0,nmax}], x]//Drop[#, 14] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=14}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 75}], x], k]] (* G. C. Greubel, Sep 07 2023 *)
  • PARI
    my(x='x+O('x^40)); Vec((eta(-x)-1)^14) \\ Joerg Arndt, Sep 07 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=75; k=14;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047639_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047639_list(m); a[k:] # G. C. Greubel, Sep 07 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^14. - G. C. Greubel, Sep 07 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021

A047640 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^15 in powers of x.

Original entry on oeis.org

1, -15, 105, -455, 1350, -2793, 3625, -765, -9840, 29120, -48657, 47370, 1680, -111060, 252555, -343526, 267540, 63210, -623510, 1216425, -1495173, 1093210, 166425, -2073645, 3963260, -4864839, 3872295, -618310, -4345470, 9477960, -12611991
Offset: 15

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Crossrefs

Programs

  • Magma
    m:=80;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^(15) )); // G. C. Greubel, Sep 07 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 15):
    seq(a(n), n=15..45);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=45; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] - 1)^15, {x, 0, nmax}], x]//Drop[#, 15] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    With[{k=15}, Drop[CoefficientList[Series[(QPochhammer[-x] -1)^k, {x,0, 75}], x], k]] (* G. C. Greubel, Sep 07 2023 *)
  • PARI
    my(x='x+O('x^40)); Vec((eta(-x)-1)^15) \\ Joerg Arndt, Sep 07 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=75; k=15;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A047640_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A047640_list(m); a[k:] # G. C. Greubel, Sep 07 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^15. - G. C. Greubel, Sep 07 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021
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