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.

Previous Showing 11-17 of 17 results.

A369764 Maximal coefficient of (1 - x) * (1 - x^8) * (1 - x^27) * ... * (1 - x^(n^3)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 7, 7, 7, 8, 11, 18, 23, 28, 32, 40, 55, 58, 81, 118, 128, 171, 204, 327, 395, 555, 843, 1009, 1580, 2254, 3224, 4703, 6999, 4573, 6255, 7760, 12563, 15626, 22328, 33788, 47750, 51522, 84103, 120853, 168565, 312262, 306080
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 31 2024

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) b(n):= `if`(n=0, 1, expand(b(n-1)*(1-x^(n^3)))) end:
    a:= n-> max(coeffs(b(n))):
    seq(a(n), n=0..52);  # Alois P. Heinz, Jan 31 2024
  • Mathematica
    b[n_] := b[n] = If[n == 0, 1, Expand[b[n-1]*(1-x^(n^3))]];
    a[n_] := Max[CoefficientList[b[n], x]];
    Table[a[n], {n, 0, 52}] (* Jean-François Alcover, Jul 07 2025, after Alois P. Heinz *)
  • PARI
    a(n)=vecmax(Vec(prod(k=1,n,1-x^(k^3))));
    vector(30,n,a(n-1)) \\ Joerg Arndt, Jan 31 2024
    
  • Python
    from collections import Counter
    def A369764(n):
        c = {0:1,1:-1}
        for i in range(2,n+1):
            d = Counter(c)
            for k in c:
                d[k+i**3] -= c[k]
            c = d
        return max(c.values()) # Chai Wah Wu, Jan 31 2024

Formula

Trivial bounds: 1 <= a(n) <= 2^n. - Charles R Greathouse IV, Jul 07 2025

Extensions

a(45)-a(52) from Alois P. Heinz, Jan 31 2024

A369774 Maximal coefficient of (1 - x) * (1 - x - x^2) * ... * (1 - x - x^2 - ... - x^n).

Original entry on oeis.org

1, 1, 1, 2, 3, 8, 13, 63, 167, 1227, 5240, 46958, 297080, 3108808, 26714243, 325635647, 3535022425, 49403859787, 646713449897, 10221697892707, 156049674957354, 2756431502525358, 48028121269507891, 940216720983170113, 18359095114316009613
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 31 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[(1 - Sum[x^j, {j, 1, i}]), {i, 1, n}], x]], {n, 0, 24}]
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, 1 - sum(i=1, k, x^i)))); \\ Michel Marcus, Feb 01 2024
    
  • Python
    from collections import Counter
    def A369774(n):
        c = {0:1}
        for k in range(1,n+1):
            d = Counter(c)
            for j in c:
                a = c[j]
                for i in range(1,k+1):
                    d[j+i] -= a
            c = d
        return max(c.values()) # Chai Wah Wu, Feb 01 2024

A301705 a(n) is the number of zero coefficients of the polynomial (x-1)*(x^2-1)*...*(x^n-1) below the leading coefficient.

Original entry on oeis.org

0, 0, 1, 4, 4, 8, 11, 12, 14, 20, 25, 26, 24, 42, 37, 40, 46, 46, 45, 50, 62, 62, 69, 72, 80, 78, 79, 74, 88, 94, 97, 102, 94, 104, 105, 106, 102, 116, 137, 130, 126, 132, 121, 122, 134, 152, 155, 160, 164, 156, 143, 156, 170, 172, 167, 178, 186, 194, 185, 168, 174, 176, 183, 182, 192, 194, 205, 196, 200, 188
Offset: 1

Views

Author

Ovidiu Bagdasar, Mar 25 2018

Keywords

Examples

			Denote P_n(x) = (x-1)...(x^n-1).
P_1(x) = x-1, hence a(1)=0.
P_2(x) = (x-1)*(x^2-1) = x^3-x^2-x+1, hence a(2)=0;
P_3(x) = (x-1)*(x^2-1)*(x^3-1) = x^6-x^5-x^4+x^2+x-1, hence a(3)=1;
P_4(x) = (x-1)*(x^2-1)*(x^3-1)*(x^4-1) = x^10 - x^9 - x^8+2x^5-x^2-x+1, hence a(4)=4.
		

Crossrefs

Programs

  • Maple
    a:= n-> add(`if`(i=0, 1, 0), i=[(p-> seq(coeff(p, x, i),
             i=0..degree(p)))(expand(mul(x^i-1, i=1..n)))]):
    seq(a(n), n=1..70);  # Alois P. Heinz, Mar 29 2019
  • Mathematica
    Rest@ Array[Count[CoefficientList[Times @@ Array[x^# - 1 &, # - 1], x], ?(# == 0 &)] &, 71] (* _Michael De Vlieger, Mar 29 2019 *)
  • PARI
    a(n) = #select(x->(x==0), Vec((prod(k=1, n, (x^k-1))))); \\ Michel Marcus, Apr 02 2018

Formula

a(n) = 1+n(n+1)/2-A086781(n).

A369705 Maximal coefficient of (1 + x) * (1 - x^2) * (1 + x^3) * ... * (1 - (-x)^n).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 2, 2, 3, 3, 4, 6, 5, 6, 7, 7, 8, 10, 11, 16, 16, 19, 21, 23, 28, 34, 41, 50, 56, 68, 80, 91, 110, 135, 158, 196, 225, 269, 320, 376, 447, 544, 644, 786, 921, 1111, 1321, 1573, 1882, 2274, 2711, 3280, 3895, 4694, 5591, 6718
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 29 2024

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, expand(b(n-1)*(1-(-x)^n))) end:
    a:= n-> max(coeffs(b(n))):
    seq(a(n), n=0..60);  # Alois P. Heinz, Jan 29 2024
  • Mathematica
    Table[Max[CoefficientList[Product[(1 - (-x)^k), {k, 1, n}], x]], {n, 0, 60}]
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, (1-(-x)^k)))); \\ Michel Marcus, Jan 30 2024

A369984 Maximum coefficient of (1 - x) * (1 - x^3) * (1 - x^6) * ... * (1 - x^(n*(n+1)/2)).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 3, 3, 5, 4, 5, 4, 8, 10, 9, 13, 16, 26, 36, 38, 51, 66, 48, 36, 49, 49, 94, 147, 152, 174, 120, 214, 268, 346, 580, 463, 598, 1024, 1217, 1521, 2473, 2417, 3340, 4795, 7086, 12643, 4808, 5569, 9373, 13083, 9644, 8762, 9516, 10702, 14483
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 07 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[(1 - x^(k (k + 1)/2)), {k, 1, n}], x]], {n, 0, 55}]
  • PARI
    a(n) = vecmax(Vec(prod(i=1, n, (1-x^(i*(i+1)/2))))); \\ Michel Marcus, Feb 07 2024

A369726 Maximal coefficient of (1 - x) * (1 - x^2)^2 * (1 - x^3)^3 * ... * (1 - x^n)^n.

Original entry on oeis.org

1, 1, 2, 5, 30, 289, 5170, 155768, 7947236, 695357704, 105014923458, 26823702973095, 12124672181643014, 9302296598744837059, 12142590791028740988194, 26874517085010633423659616, 100413718348008543669377307304, 634527279123990475683817934978079
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 30 2024

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> max(coeffs(expand(mul((1-x^k)^k, k=1..n)))):
    seq(a(n), n=0..17);  # Alois P. Heinz, Jan 30 2024
  • Mathematica
    Table[Max[CoefficientList[Product[(1 - x^k)^k, {k, 1, n}], x]], {n, 0, 17}]
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, (1-x^k)^k))); \\ Michel Marcus, Jan 30 2024

A369727 Maximal coefficient of ( (1 - x) * (1 - x^2) * (1 - x^3) * ... * (1 - x^n) )^n.

Original entry on oeis.org

1, 1, 4, 15, 226, 2630, 95420, 4177117, 371458250, 49558386762, 11496848193144, 4055873729544890, 2321900139799896688, 2052844416093203835934, 2864423943667784141723196, 6181759121650271558049171285, 20773297302068160010868731066114
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 30 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[(1 - x^k)^n, {k, 1, n}], x]], {n, 0, 16}]
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, (1-x^k))^n)); \\ Michel Marcus, Jan 30 2024
Previous Showing 11-17 of 17 results.