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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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

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

A298948 Expansion of Product_{k>=1} (1 - x^prime(k))^2.

Original entry on oeis.org

1, 0, -2, -2, 1, 2, 1, 0, 2, 2, -2, -6, -2, 2, 2, 0, 3, 2, -1, -6, -2, 2, 3, -2, 4, 6, 0, -10, -4, 0, 4, -2, 5, 8, 6, -12, -6, -4, -1, -6, 12, 10, 8, -12, -4, -4, 1, -18, 11, 18, 15, -20, -2, -8, 7, -18, 8, 12, 29, -24, 2, -8, 3, -34, 21, 6, 29, -32, 5, -8, 31, -52
Offset: 0

Views

Author

Seiichi Manyama, Jan 30 2018

Keywords

Comments

Self-convolution of A046675.

Crossrefs

A300521 Expansion of Product_{k>=1} (1 - x^prime(k))^prime(k).

Original entry on oeis.org

1, 0, -2, -3, 1, 1, 3, 0, 9, 8, 4, -31, -12, -13, 20, -13, 48, -17, 74, -87, 8, -143, 175, -174, 349, -164, 369, -651, 520, -1004, 1142, -1218, 1652, -1739, 3291, -3933, 3546, -5743, 6170, -8022, 11435, -13230, 17196, -18706, 22958, -31884, 38420, -49802, 58916
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 08 2018

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 48; CoefficientList[Series[Product[(1 - x^Prime[k])^Prime[k], {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 48; CoefficientList[Series[Exp[-Sum[DivisorSum[k, Boole[PrimeQ[#]] #^2 &] x^k/k, {k, 1, nmax}]], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 - x^A000040(k))^A000040(k).
G.f.: exp(-Sum_{k>=1} A005063(k)*x^k/k).
Previous Showing 11-14 of 14 results.