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 1-4 of 4 results.

A179998 Numbers which are members of both A000140 and A039909.

Original entry on oeis.org

1, 2, 101, 573, 3836, 29228, 250749, 2409581, 3727542188, 50626553988, 738680521142, 11501573822788, 190418421447330, 3344822488498265, 24965661442811799655, 538134522243713149122, 12140037056605135928410
Offset: 1

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Author

Paul Muljadi, Jan 13 2011

Keywords

Programs

  • Magma
    PS:=PowerSeriesRing(Integers()); { Max(Coefficients(&*[&+[ x^i: i in [0..j] ]: j in [0..n-1] ])): n in [1..25] } meet { Max(Coefficients(&*[&+[ (-x)^i: i in [0..j] ]: j in [0..n] ])): n in [1..24] }; // Klaus Brockhaus, Jan 18 2011

A039830 Number of different coefficient values in expansion of Product_{i=1..n} (1-q^1+q^2-...+(-q)^i).

Original entry on oeis.org

1, 2, 4, 4, 6, 16, 22, 15, 19, 46, 56, 34, 40, 92, 106, 61, 69, 154, 172, 96, 106, 232, 254, 139, 151, 326, 352, 190, 204, 436, 466, 249, 265, 562, 596, 316, 334, 704, 742, 391, 411, 862, 904, 474, 496, 1036, 1082, 565, 589, 1226, 1276, 664, 690, 1432, 1486, 771
Offset: 0

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Author

Keywords

Crossrefs

Extensions

a(0)=1 prepended by Seiichi Manyama, Jan 05 2023

A369773 Maximal coefficient of (1 + x) * (1 + x - x^2) * ... * (1 + x - x^2 + ... - (-x)^n).

Original entry on oeis.org

1, 1, 2, 3, 4, 6, 19, 59, 233, 1189, 7046, 45326, 356517, 3108808, 30028121, 325635647, 3830546752, 49403859787, 685063715374, 10162709827329, 162776892315940, 2754021620252692, 49463507801582609, 940216720983170113, 18786988751008626812
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}]
  • Python
    from collections import Counter
    def A369773(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 if i&1 else -a)
            c = d
        return max(c.values()) # Chai Wah Wu, Feb 01 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
Showing 1-4 of 4 results.