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 10 results.

A359328 Maximal coefficient of x^2*(x^2 + x^3)*(x^2 + x^3 + x^5)*...*(x^2 + x^3 + x^5 + ... + x^prime(n)).

Original entry on oeis.org

1, 1, 1, 2, 4, 12, 46, 251, 1576, 11578, 94933, 875134, 8900088, 99276703, 1214131109, 16107824706, 229757728186, 3499486564517, 56862172844198, 980725126968577, 17899265342632635, 345197504845310134, 7005723403640260805, 149261757412790940113, 3329108788695272565243
Offset: 0

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Author

Stefano Spezia, Dec 26 2022

Keywords

Comments

Excluding the term 1 from A326178, the exponents of the product x^0*x^2*(x^2 + x^3)*(x^2 + x^3 + x^5)*...*(x^2 + x^3 + x^5 + ... + x^prime(n)) are given by all the other terms of A326178.
a(n) is the number of compositions of the terms of the n-th row of A359337 into n prime parts less than or equal to prime(n), with the first part equal to 2, the second part less than or equal to 3, ..., and the n-th part less than or equal to prime(n).

Crossrefs

Cf. A359337 (corresponding exponents), A359338 (minimal corresponding exponent), A359339 (maximal corresponding exponent).

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[Sum[x^Prime[i],{i,k}],{k,n}],x]],{n,0,24}]
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, sum(i=1, k, x^prime(i))))); \\ Michel Marcus, Dec 27 2022
    
  • Python
    from collections import Counter
    from sympy import prime, primerange
    def A359328(n):
        if n == 0: return 1
        c, p = {0:1}, list(primerange(prime(n)+1))
        for k in range(1,n+1):
            d = Counter()
            for j in c:
                a = c[j]
                for i in p[:k]:
                    d[j+i] += a
            c = d
        return max(c.values()) # Chai Wah Wu, Feb 01 2024

A350514 Maximal coefficient of Product_{j=1..n} (1 - x^prime(j)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 4, 6, 8, 12, 17, 30, 41, 70, 107, 186, 307, 531, 887, 1561, 2701, 4817, 8514, 15030, 26490, 47200, 84622, 151809, 273912, 496807, 900595, 1643185, 2999837, 5498916, 10111429, 18596096, 34306158, 63585519, 118215700
Offset: 0

Views

Author

Alois P. Heinz, Jan 02 2022

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1,
          expand((1-x^ithprime(n))*b(n-1)))
        end:
    a:= n-> max(coeffs(b(n))):
    seq(a(n), n=0..60);
  • Mathematica
    a[n_] := Times@@(1-x^Prime[Range[n]])//Expand//CoefficientList[#, x]&//Max;
    Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Jun 02 2022 *)
  • PARI
    a(n) = vecmax(Vec(prod(j=1, n, 1-'x^prime(j)))); \\ Michel Marcus, Jan 04 2022
  • Python
    from sympy.abc import x
    from sympy import prime, prod
    def A350514(n): return 1 if n == 0 else max(prod(1-x**prime(i) for i in range(1,n+1)).as_poly().coeffs()) # Chai Wah Wu, Jan 04 2022
    

A367843 Maximum of the absolute value of the coefficients of (1 - x^2) * (1 - x^3) * (1 - x^5) * ... * (1 - x^prime(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 6, 8, 12, 18, 30, 46, 70, 113, 186, 314, 531, 894, 1561, 2705, 4817, 8514, 15030, 26502, 47200, 84698, 151809, 273961, 496807, 900596, 1643185, 2999837, 5498916, 10111429, 18596096, 34306158, 63585519, 118215700
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 06 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[Abs[CoefficientList[Product[(1 - x^Prime[k]), {k, 1, n}], x]]], {n, 0, 46}]
  • Python
    from collections import Counter
    from sympy import prime
    def A367843(n):
        c = {0:1}
        for k in range(1,n+1):
            p, b = prime(k), Counter(c)
            for j in c:
                b[j+p] -= c[j]
            c = b
        return max(map(abs,c.values())) # Chai Wah Wu, Feb 06 2024

A369708 Maximal coefficient of (1 + x^3) * (1 + x^5) * (1 + x^7) * ... * (1 + x^prime(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 4, 5, 8, 14, 23, 40, 70, 126, 221, 394, 711, 1290, 2354, 4344, 8015, 14868, 27585, 51094, 95160, 178436, 335645, 634568, 1202236, 2261052, 4267640, 8067296, 15318171, 29031484, 55248527, 105251904, 200711160, 383580180, 733704990
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 29 2024

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, 1, expand(b(n-1)*(1+x^ithprime(n)))) end:
    a:= n-> max(coeffs(b(n))):
    seq(a(n), n=0..40);  # Alois P. Heinz, Jan 29 2024
  • Mathematica
    Table[Max[CoefficientList[Product[(1 + x^Prime[k]), {k, 2, n}], x]], {n, 0, 40}]
  • PARI
    a(n) = vecmax(Vec(prod(i=2, n, 1+x^prime(i)))); \\ Michel Marcus, Jan 29 2024
    
  • Python
    from collections import Counter
    from sympy import prime
    def A369708(n):
        c = {0:1}
        for i in range(2,n+1):
            p, d = prime(i), Counter(c)
            for k in c:
                d[k+p] += c[k]
            c = d
        return max(c.values()) # Chai Wah Wu, Jan 31 2024

A350504 Maximal coefficient of (1 + x) * (1 + x^3) * (1 + x^5) * ... * (1 + x^(2*n-1)).

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 3, 5, 8, 13, 22, 38, 68, 118, 211, 380, 692, 1262, 2316, 4277, 7930, 14745, 27517, 51541, 96792, 182182, 343711, 650095, 1231932, 2338706, 4447510, 8472697, 16164914, 30884150, 59086618, 113189168, 217091832, 416839177, 801247614, 1541726967, 2969432270
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 28 2022

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1,
          expand((1+x^(2*n-1))*b(n-1)))
        end:
    a:= n-> max(coeffs(b(n))):
    seq(a(n), n=0..40);  # Alois P. Heinz, Jan 28 2022
  • Mathematica
    b[n_] := b[n] = If[n == 0, 1, Expand[(1 + x^(2*n - 1))*b[n - 1]]];
    a[n_] := Max[CoefficientList[b[n], x]];
    Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Mar 01 2022, after Alois P. Heinz *)
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, 1+x^(2*k-1)))); \\ Seiichi Manyama, Jan 28 2021

Formula

a(n) ~ sqrt(3) * 2^(n - 1/2) / (sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Feb 04 2022

A369765 Maximal coefficient of (1 + x) * (1 + x^2) * (1 + x^3) * (1 + x^5) * ... * (1 + x^prime(n-1)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 3, 6, 7, 13, 19, 32, 53, 90, 156, 277, 494, 878, 1566, 2836, 5146, 9401, 17358, 32042, 59434, 110292, 204332, 380548, 713601, 1342448, 2538012, 4808578, 9043605, 17070234, 32268611, 61271738, 116123939, 220993892, 421000142, 802844420, 1534312896
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 31 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[(1 + x^If[k == 1, 1, Prime[k - 1]]), {k, 1, n}], x]], {n, 0, 40}]
  • Python
    from collections import Counter
    from sympy import prime
    def A369765(n):
        c = {0:1,1:1}
        for k in range(1,n):
            p, d = prime(k), Counter(c)
            for j in c:
                d[j+p] += c[j]
            c = d
        return max(c.values()) # Chai Wah Wu, Feb 01 2024

A369775 Maximal coefficient of (1 + x^2) * (1 + x^2 + x^3) * (1 + x^2 + x^3 + x^5) * ... * (1 + x^2 + ... + x^prime(n)).

Original entry on oeis.org

1, 1, 2, 5, 16, 65, 293, 1807, 12946, 106475, 972260, 9858553, 109451903, 1323071345, 17398667717, 247055196932, 3753507625272, 60680317203979, 1043036844360792, 18969267205680868, 364107881070036688, 7366172106829696356, 156467911373737550264
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 31 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[CoefficientList[Product[(1 + Sum[x^Prime[j], {j, 1, i}]), {i, 1, n}], x]], {n, 0, 22}]
  • PARI
    a(n) = vecmax(Vec(prod(k=1, n, 1 + sum(i=1, k, x^prime(i))))); \\ Michel Marcus, Feb 01 2024
    
  • Python
    from collections import Counter
    from sympy import prime, primerange
    def A369775(n):
        if n == 0: return 1
        c, p = {0:1}, list(primerange(prime(n)+1))
        for k in range(1,n+1):
            d = Counter(c)
            for j in c:
                a = c[j]
                for i in p[:k]:
                    d[j+i] += a
            c = d
        return max(c.values()) # Chai Wah Wu, Feb 01 2024

A379563 Smallest degree of x with the largest coefficient in Product_{k=1..n} (1 + x^prime(k)).

Original entry on oeis.org

0, 0, 0, 5, 5, 5, 18, 18, 35, 42, 58, 73, 89, 114, 137, 163, 190, 220, 249, 281, 318, 356, 393, 437, 480, 530, 580, 632, 685, 740, 796, 860, 925, 994, 1063, 1138, 1213, 1292, 1373, 1457, 1543, 1633, 1723, 1819, 1915, 2014, 2113, 2219, 2330, 2444, 2558, 2675, 2794, 2915, 3040, 3169
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 26 2024

Keywords

Crossrefs

A379564 Largest degree of x with the largest coefficient in Product_{k=1..n} (1 + x^prime(k)).

Original entry on oeis.org

0, 2, 5, 5, 12, 23, 23, 40, 42, 58, 71, 87, 108, 124, 144, 165, 191, 220, 252, 287, 321, 356, 398, 437, 483, 530, 581, 632, 686, 740, 797, 860, 926, 994, 1064, 1138, 1214, 1292, 1374, 1457, 1544, 1633, 1724, 1819, 1916, 2014, 2114, 2219, 2331, 2444, 2559, 2675, 2795, 2915, 3041, 3169
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 26 2024

Keywords

Crossrefs

A379976 Absolute value of the minimum coefficient of (1 - x^2) * (1 - x^3) * (1 - x^5) * ... * (1 - x^prime(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 4, 6, 8, 12, 18, 30, 46, 70, 113, 186, 314, 531, 894, 1561, 2705, 4817, 8502, 15030, 26502, 47200, 84698, 151809, 273961, 496807, 900596, 1643185, 2999067, 5498916, 10110030, 18596096, 34300223, 63585519, 118208807, 219235308, 405259618, 752027569, 1400505025
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 07 2025

Keywords

Crossrefs

Programs

  • Maple
    P:= 1: R:= 1:
    for i from 1 to 100 do
      P:= P * (1 - x^ithprime(i));
      R:= R, abs(min(coeffs(expand(P),x)))
    od:
    R; # Robert Israel, Feb 07 2025
  • Mathematica
    Table[Min[CoefficientList[Product[(1 - x^Prime[k]), {k, 1, n}], x]], {n, 0, 50}] // Abs
  • PARI
    a(n) = abs(vecmin(Vec(prod(k=1, n, 1-x^prime(k))))); \\ Michel Marcus, Jan 18 2025
Showing 1-10 of 10 results.