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.

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A369711 Maximum coefficient of (1 - x)^3 * (1 - x^2)^3 * (1 - x^3)^3 * ... * (1 - x^n)^3.

Original entry on oeis.org

1, 3, 8, 15, 44, 50, 117, 186, 356, 561, 969, 1761, 3508, 5789, 10347, 19023, 35580, 62388, 111255, 205653, 376496, 674085, 1201809, 2211462, 4056220, 7287672, 13027698, 24005627, 43800562, 79033269, 141583272, 260061408, 473603594, 855436899, 1532383878, 2813222766
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 29 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[(1 - x^k)^3, {k, 1, n}], x]], {n, 0, 35}]
  • PARI
    a(n) = vecmax(Vec(prod(i=1, n, (1-x^i)^3))); \\ Michel Marcus, Jan 29 2024
    
  • Python
    from collections import Counter
    def A369711(n):
        c = {0:1}
        for k in range(1,n+1):
            d = Counter(c)
            for j in c:
                a = c[j]
                d[j+k] -= 3*a
                d[j+2*k] += 3*a
                d[j+3*k] -= a
            c = d
        return max(c.values()) # Chai Wah Wu, Feb 07 2024

A171805 G.f.: Series reversion of x/P(x)^3 where P(x) is the g.f. for Partition numbers (A000041).

Original entry on oeis.org

1, 3, 18, 130, 1044, 8946, 80135, 741312, 7027515, 67911855, 666525630, 6625647054, 66570488901, 674964968175, 6897258376218, 70961851119848, 734455079297433, 7641851681095236, 79886815507105175, 838655487787502616, 8837797224686207976, 93454820274339167191
Offset: 1

Views

Author

Paul D. Hanna, Dec 20 2009

Keywords

Examples

			G.f.: A(x) = x + 3*x^2 + 18*x^3 + 130*x^4 + 1044*x^5 + 8946*x^6 +...
where Series_Reversion(A(x)) = x/P(x)^3 = x*eta(x)^3 and
x*eta(x)^3 = x - 3*x^2 + 5*x^4 - 7*x^7 + 9*x^11 - 11*x^16 + 13*x^22 +...
		

Crossrefs

Programs

  • Mathematica
    InverseSeries[x QPochhammer[x]^3 + O[x]^30][[3]] (* Vladimir Reshetnikov, Nov 21 2016 *)
    (* Calculation of constants {d,c}: *) eq = FindRoot[{r/QPochhammer[s]^3 == s, 1/s + 3*(s/r)^(1/3)*Derivative[0, 1][QPochhammer][s, s] == (3*(Log[1 - s] + QPolyGamma[0, 1, s]))/(s*Log[s])}, {r, 1/10}, {s, 1/8}, WorkingPrecision -> 1000]; {N[1/r /. eq, 120], val = Sqrt[r*(-1 + s)*s^2*(Log[s]^2/(6*Pi*(r*(-4*s*ArcTanh[1 - 2*s] + Log[1 - s]*(2 + 3*(-1 + s)*Log[1 - s] + Log[s] - s*Log[s])) - (-1 + s)*(-3*r*QPolyGamma[0, 1, s]^2 + r*QPolyGamma[1, 1, s] + QPolyGamma[0, 1, s]*(r*(2 - 6*Log[1 - s] + Log[s]) + 6*(r/s)^(2/3)*s^2*Log[s]* Derivative[0, 1][QPochhammer][s, s]) + s*Log[s]*((r/s)^(1/3)*s*(6*(r/s)^(1/3) * Log[1 - s] * Derivative[0, 1][QPochhammer][s, s] - 4*s*Log[s] * Derivative[0, 1][QPochhammer][s, s]^2 + (r/s)^(1/3)*s*Log[s]* Derivative[0, 2][QPochhammer][s, s]) - 2*r*Derivative[0, 0, 1][ QPolyGamma][0, 1, s])))))] /. eq; N[Chop[val], -Floor[Log[10, Abs[Im[val]]]] - 3]} (* Vaclav Kotesovec, Oct 03 2023 *)
  • PARI
    {a(n)=polcoeff(serreverse(x*eta(x+x*O(x^n))^3),n)}

Formula

G.f. A(x) satisfies:
(1) A(x) = x/Product_{n>=1} (1 - A(x)^n)^3 ;
(2) A(x) = x/Sum_{n>=0} (-1)^n*(2n+1)*A(x)^(n(n+1)/2).
G.f.: A(x) = Series_Reversion(x*eta(x)^3) where eta(q) is the q-expansion of the Dedekind eta function without the q^(1/24) factor (A010815).
Self-convolution cube of A171804 (with offset).
a(n) ~ c * d^n / n^(3/2), where d = 11.34340769381039824727582112969136186... and c = 0.05972244738388663765328174469956... - Vaclav Kotesovec, Nov 11 2017

Extensions

More terms from Vladimir Reshetnikov, Nov 21 2016

A198954 Expansion of the rotational partition function for a heteronuclear diatomic molecule.

Original entry on oeis.org

1, 3, 0, 5, 0, 0, 7, 0, 0, 0, 9, 0, 0, 0, 0, 11, 0, 0, 0, 0, 0, 13, 0, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 0, 0, 17, 0, 0, 0, 0, 0, 0, 0, 0, 19, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 25, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 27, 0, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Michael Somos, Oct 31 2011

Keywords

Comments

The partition function of a heteronuclear diatomic molecule is Sum_{J>=0} (2*J + 1) * exp( - J * (J + 1) * hbar^2 / (2 * I * k * T)) where I is the moment of inertia, hbar is reduced Planck's constant, k is Boltzmann's constant, and T is temperature. The degeneracy for the J-th energy level is 2*J + 1.
As triangle: triangle T(n,k), read by rows, given by (3,-4/3,1/3,0,0,0,0,0,0,0,...) DELTA (0,0,0,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938. - Philippe Deléham, Nov 01 2011
Note that the g.f. theta_1'(0, q^(1/2)) / (2 * q^(1/8)) = 1 - 3*q + 5*q^3 - 7*q^6 + 9*q^10 + ... which is the same as this sequence except the signs alternate. - Michael Somos, Aug 26 2015

Examples

			G.f. = 1 + 3*x + 5*x^3 + 7*x^6 + 9*x^10 + 11*x^15 + 13*x^21 + 15*x^28 + ...
G.f. = 1 + 3*q^2 + 5*q^6 + 7*q^12 + 9*q^20 + 11*q^30 + 13*q^42 + 15*q^56 + ...
Triangle begins:
   1;
   3, 0;
   5, 0, 0;
   7, 0, 0, 0;
   9, 0, 0, 0, 0;
  11, 0, 0, 0, 0, 0;
  13, 0, 0, 0, 0, 0, 0;
  15, 0, 0, 0, 0, 0, 0, 0;
  17, 0, 0, 0, 0, 0, 0, 0, 0;
		

References

  • G. H. Wannier, Statistical Physics, Dover Publications, 1987, see p. 215 equ. (11.13).

Crossrefs

Programs

  • Maple
    seq(op([2*i+1,0$i]), i=0..10); # Robert Israel, Jan 15 2015
  • Mathematica
    a[ n_] := If[ n < 0, 0, With[ {m = Sqrt[8 n + 1]}, If[ IntegerQ[m], m KroneckerSymbol[ 4, m], 0]]]; (* Michael Somos, Aug 26 2015 *)
  • PARI
    {a(n) = my(m); if( issquare( 8*n + 1, &m), m, 0)};

Formula

G.f.: Sum_{k>=0} (2*k + 1) * x^( (k^2 + k) / 2). This is related to Jacobi theta functions.
a(n) = (t*(t+1)-2*n-1)*(t-r), where t = floor(sqrt(2*(n+1))+1/2) and r = floor(sqrt(2*n)+1/2). - Mikael Aaltonen, Jan 15 2015
a(n) = A053187(2n+1) - A053187(2n). - Robert Israel, Jan 15 2015
a(n) = abs(A010816(n)). - Joerg Arndt, Jan 16 2015

A319933 A(n, k) = [x^k] DedekindEta(x)^n, square array read by descending antidiagonals, A(n, k) for n >= 0 and k >= 0.

Original entry on oeis.org

1, 0, 1, 0, -1, 1, 0, -1, -2, 1, 0, 0, -1, -3, 1, 0, 0, 2, 0, -4, 1, 0, 1, 1, 5, 2, -5, 1, 0, 0, 2, 0, 8, 5, -6, 1, 0, 1, -2, 0, -5, 10, 9, -7, 1, 0, 0, 0, -7, -4, -15, 10, 14, -8, 1, 0, 0, -2, 0, -10, -6, -30, 7, 20, -9, 1, 0, 0, -2, 0, 8, -5, 0, -49, 0, 27, -10, 1
Offset: 0

Views

Author

Peter Luschny, Oct 02 2018

Keywords

Comments

The columns are generated by polynomials whose coefficients constitute the triangle of signed D'Arcais numbers A078521 when multiplied with n!.

Examples

			[ 0] 1,   0,   0,    0,     0,    0,     0,     0,     0,     0, ... A000007
[ 1] 1,  -1,  -1,    0,     0,    1,     0,     1,     0,     0, ... A010815
[ 2] 1,  -2,  -1,    2,     1,    2,    -2,     0,    -2,    -2, ... A002107
[ 3] 1,  -3,   0,    5,     0,    0,    -7,     0,     0,     0, ... A010816
[ 4] 1,  -4,   2,    8,    -5,   -4,   -10,     8,     9,     0, ... A000727
[ 5] 1,  -5,   5,   10,   -15,   -6,    -5,    25,    15,   -20, ... A000728
[ 6] 1,  -6,   9,   10,   -30,    0,    11,    42,     0,   -70, ... A000729
[ 7] 1,  -7,  14,    7,   -49,   21,    35,    41,   -49,  -133, ... A000730
[ 8] 1,  -8,  20,    0,   -70,   64,    56,     0,  -125,  -160, ... A000731
[ 9] 1,  -9,  27,  -12,   -90,  135,    54,   -99,  -189,   -85, ... A010817
[10] 1, -10,  35,  -30,  -105,  238,     0,  -260,  -165,   140, ... A010818
    A001489,  v , A167541, v , A319931,  v ,         diagonal: A008705
           A080956       A319930      A319932
		

References

  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. Fifth ed., Clarendon Press, Oxford, 2003.

Crossrefs

Transpose of A286354.
Cf. A078521, A319574 (JacobiTheta3).

Programs

  • Julia
    # DedekindEta is defined in A000594
    for n in 0:10
        DedekindEta(10, n) |> println
    end
  • Maple
    DedekindEta := (x, n) -> mul(1-x^j, j=1..n):
    A319933row := proc(n, len) series(DedekindEta(x, len)^n, x, len+1):
    seq(coeff(%, x, j), j=0..len-1) end:
    seq(print([n], A319933row(n, 10)), n=0..10);
  • Mathematica
    eta[x_, n_] := Product[1 - x^j, {j, 1, n}];
    A[n_, k_] := SeriesCoefficient[eta[x, k]^n, {x, 0, k}];
    Table[A[n - k, k], {n, 0, 11}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Nov 10 2018 *)
  • Sage
    from sage.modular.etaproducts import qexp_eta
    def A319933row(n, len):
        return (qexp_eta(ZZ['q'], len+4)^n).list()[:len]
    for n in (0..10):
        print(A319933row(n, 10))
    

A202394 Expansion of f(-x)^3 + 9 * x * f(-x^9)^3 in powers of x where f() is a Ramanujan theta function.

Original entry on oeis.org

1, 6, 0, 5, 0, 0, -7, 0, 0, 0, -18, 0, 0, 0, 0, -11, 0, 0, 0, 0, 0, 13, 0, 0, 0, 0, 0, 0, 30, 0, 0, 0, 0, 0, 0, 0, 17, 0, 0, 0, 0, 0, 0, 0, 0, -19, 0, 0, 0, 0, 0, 0, 0, 0, 0, -42, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 25, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 54, 0, 0, 0, 0
Offset: 0

Views

Author

Michael Somos, Dec 18 2011

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).
Cubic AGM theta functions: a(q) (see A004016), b(q) (A005928), c(q) (A005882).

Examples

			G.f. = 1 + 6*x + 5*x^3 - 7*x^6 - 18*x^10 - 11*x^15 + 13*x^21 + 30*x^28 + ...
G.f. = q + 6*q^9 + 5*q^25 - 7*q^49 - 18*q^81 - 11*q^121 + 13*q^169 + 30*q^225 + ...
		

Crossrefs

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ x]^3 + 9 x QPochhammer[ x^9]^3, {x, 0, n}]; (* Michael Somos, May 26 2014 *)
  • PARI
    {a(n) = local(m); if( issquare(8*n + 1, &m), (-1)^(m \ 6) * m * ((m%3 == 0) + 1), 0)};
    
  • PARI
    {a(n) = local(A); if( n<0, 0,  A = x * O(x^n); polcoeff( eta(x + A)^3 + 9 * x * eta(x^9 + A)^3, n))};

Formula

Expansion of f(-x^3) * a(x) in powers of x where f() is a Ramanujan theta function and a() is a cubic AGM theta function.
Expansion of q^(-1/8) * (eta(q)^3 + 9 * eta(q^9)^3) in powers of q.
G.f. is a period 1 Fourier series which satisfies f(-1 / (576 t)) = 41472^(1/2) (t / i)^(3/2) g(t) where q = exp(2 Pi i t) and g() is g.f. for A116916.
G.f.: Sum_{k} -(-1)^k * (6*k - 1) * x^(3*k*(3*k - 1)/2) + Sum_{k>0} -(-1)^k * 6 * (2*k - 1) * x^(9*k*(k - 1)/2 + 1).
a(3*n + 2) = a(5*n + 2) = a(5*n + 4) = a(9*n + 4) = a(9*n + 7) = 0. a(3*n) = A116916(n). a(9*n + 1) = 6 * A010816(n). a(25*n + 3) = 5 * a(n).
a(n) nonzero if and only if n is a triangular number.

A215597 Expansion of psi(-x) * f(-x)^3 in powers of x where psi(), f() are Ramanujan theta functions.

Original entry on oeis.org

1, -4, 3, 4, -2, 0, -11, 4, 0, 12, 10, -12, -7, -4, 0, -12, 16, 0, 6, 0, 9, 8, -10, 0, -18, -20, 0, 20, -14, 12, 11, 24, 0, 0, -22, 0, 16, -20, -6, -12, 0, 0, -3, 4, 0, -20, 48, 0, 14, 28, 0, -40, 0, 0, 0, -8, -33, -4, -26, 0, 30, 28, 0, 0, 2, 12, -16, 20, 0
Offset: 0

Views

Author

Michael Somos, Aug 16 2012

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			1 - 4*x + 3*x^2 + 4*x^3 - 2*x^4 - 11*x^6 + 4*x^7 + 12*x^9 + 10*x^10 + ...
q - 4*q^5 + 3*q^9 + 4*q^13 - 2*q^17 - 11*q^25 + 4*q^29 + 12*q^37 + 10*q^41 + ...
		

Crossrefs

Programs

  • Mathematica
    A215597[n_] := SeriesCoefficient[(QPochhammer[x]^4 * QPochhammer[x^4])/ QPochhammer[x^2], {x, 0, n}]; Table[A215597[n], {n, 0, 50}] (* G. C. Greubel, Oct 01 2017 *)
  • PARI
    {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x + A)^4 * eta(x^4 + A) / eta(x^2 + A), n))}

Formula

Expansion of q^(-1/4) * eta(q)^4 * eta(q^4) / eta(q^2) in powers of q.
Euler transform of period 4 sequence [ -4, -3, -4, -4, ...].
G.f. is a period 1 Fourier series which satisfies f(-1 / (128 t)) = 2^(19/2) (t/i)^2 g(t) where q = exp(2 Pi i t) and g() is the g.f. for A215596.
a(n) = (-1)^floor( n/2 ) * b(4*n + 1) where b() is multiplicative with b(2^e) = 0^e, b(p^e) = (1 + (-1)^e) / 2 * (-p)^(e/2) if p == 3 (mod 4),
Convolution of A106459 and A010816.

A227317 Expansion of psi(x)^6 * phi(-x)^2 in powers of x where phi(), psi() are Ramanujan theta functions.

Original entry on oeis.org

1, 2, -5, -10, 5, 6, 10, 40, -20, -50, 19, -52, -30, 50, -25, 74, 97, 50, -25, -140, 69, -34, -100, -50, -185, -6, 83, 310, -60, -60, 410, -128, 145, -100, -245, 250, -87, -90, -400, -410, -151, 362, 185, -50, 285, 30, 150, -240, 500, 370, -68, 222, 5, -190
Offset: 0

Views

Author

Michael Somos, Sep 02 2013

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			1 + 2*x - 5*x^2 - 10*x^3 + 5*x^4 + 6*x^5 + 10*x^6 + 40*x^7 - 20*x^8 + ...
q^3 + 2*q^7 - 5*q^11 - 10*q^15 + 5*q^19 + 6*q^23 + 10*q^27 + 40*q^31 + ...
		

Crossrefs

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ (QPochhammer[ q^2]^5 / QPochhammer[ q])^2, {q, 0, n}]
  • PARI
    {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( (eta(x^2 + A)^5 / eta(x + A))^2, n))}

Formula

Expansion of psi(x)^5 * f(-x)^3 = psi(x)^2 * f(-x^2)^6 in powers of x where psi(), f() are Ramanujan theta functions.
Expansion of q^(-3/4) * (eta(q^2)^5 / eta(x))^2 in powers of q.
Euler transform of period 2 sequence [ 2, -8, ...].
G.f. is a period 1 Fourier series which satisfies f(-1 / (32 t)) = 128 (t / i)^4 g(t) where q = exp(2 Pi i t) and g() is the g.f. for A227695.
G.f.: (Product_{k>0} (1 - x^(2*k))^5 / (1 - x^k))^2.
Convolution of A008439 and A010816.
-8 * a(n) = A215600(2*n + 1).

A369790 Number of different coefficient values in expansion of Product_{k=1..n} (1-x^k)^3.

Original entry on oeis.org

1, 4, 5, 15, 13, 31, 26, 57, 42, 91, 66, 139, 95, 209, 129, 283, 171, 365, 216, 463, 272, 573, 333, 697, 401, 825, 468, 993, 545, 1139, 629, 1315, 725, 1509, 815, 1689, 920, 1921, 1030, 2139, 1147, 2367, 1261, 2619, 1391, 2861, 1521, 3135, 1659, 3409, 1802, 3703, 1952
Offset: 0

Views

Author

Seiichi Manyama, Feb 01 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = #Set(Vec(prod(k=1, n, (1-x^k)^3)));
    
  • Python
    from collections import Counter
    def A369790(n):
        c = {0:1}
        for k in range(1,n+1):
            d = Counter(c)
            for j in c:
                a = c[j]
                d[j+k] -= 3*a
                d[j+2*k] += 3*a
                d[j+3*k] -= a
            c = d
        return len(set(c.values()))+int(max(c)+1>len(c)) # Chai Wah Wu, Feb 01 2024

A274094 a(0)=0; thereafter (-1)^(n+1)*n appears n times.

Original entry on oeis.org

0, 1, -2, -2, 3, 3, 3, -4, -4, -4, -4, 5, 5, 5, 5, 5, -6, -6, -6, -6, -6, -6, 7, 7, 7, 7, 7, 7, 7, -8, -8, -8, -8, -8, -8, -8, -8, 9, 9, 9, 9, 9, 9, 9, 9, 9, -10, -10, -10, -10, -10, -10, -10, -10, -10, -10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, -12, -12, -12, -12, -12, -12, -12, -12, -12, -12
Offset: 0

Views

Author

N. J. A. Sloane, Jun 10 2016

Keywords

Crossrefs

Partial sums of A010816.

Programs

  • Maple
    s1:=[0];
    for n from 1 to 15 do
    for i from 1 to n do
    s1:=[op(s1),(-1)^(n+1)*n]; od: od:
    s1;
  • Mathematica
    Join[{0}, Flatten[Table[(-1)^(n+1)*n, {n, 15}, {n}]]] (* Paolo Xausa, Sep 30 2024 *)
    Join[{0},Flatten[Table[PadRight[{},n,(-1)^(n+1) n],{n,15}]]] (* Harvey P. Dale, Nov 28 2024 *)
  • Python
    A274094_list = [0]+ [i for n in range(1,142) for i in [n if n % 2 else -n]*n] # Chai Wah Wu, Jun 11 2016
    
  • Python
    from math import isqrt
    def A274094(n): return m if (m:=isqrt(n<<3)+1>>1)&1 else -m # Chai Wah Wu, Nov 05 2024

A303992 Triangular array T(n,k) giving coefficients in expansion of Product_{j=1..n} (1-x^j)^3.

Original entry on oeis.org

1, 1, -3, 3, -1, 1, -3, 0, 8, -6, -6, 8, 0, -3, 1, 1, -3, 0, 5, 3, -6, -13, 9, 15, 0, -15, -9, 13, 6, -3, -5, 0, 3, -1, 1, -3, 0, 5, 0, 3, -13, -6, 9, 9, 24, -21, -24, -9, 3, 44, 3, -9, -24, -21, 24, 9, 9, -6, -13, 3, 0, 5, 0, -3, 1
Offset: 0

Views

Author

Seiichi Manyama, May 04 2018

Keywords

Examples

			Irregular triangle starts:
n\k| 0   1  2   3   4   5    6  7   8  9   10  11  12 13  14  15 16 17  18
---+-----------------------------------------------------------------------
0  | 1;
1  | 1, -3, 3, -1;
2  | 1, -3, 0,  8, -6, -6,   8, 0, -3, 1;
3  | 1, -3, 0,  5,  3, -6, -13, 9, 15, 0, -15, -9, 13, 6, -3, -5, 0, 3, -1;
		

Crossrefs

Programs

  • PARI
    T(n, k) = polcoef(prod(j=1, n, (1-x^j)^3), k);
    tabf(nn) = for(n=0, nn, for(k=0, 3*n*(n+1)/2, print1(T(n, k), ", ")); print)
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