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 38 results. Next

A024327 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor( (n+1)/2 ), s = A023531, t = A014306.

Original entry on oeis.org

0, 0, 1, 1, 0, 1, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 4, 3, 4, 4, 4, 4, 3, 4, 4, 3, 4, 4, 3, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 6, 5, 6, 6, 5, 6, 6, 5, 5, 6, 6, 5, 6, 6, 6, 6, 5, 7, 7, 7, 7, 7, 6, 7, 7, 7, 7, 7, 7, 6, 7, 7, 6, 7, 8, 7, 8, 7
Offset: 1

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Crossrefs

Programs

  • Mathematica
    A014306:= With[{ms= Table[m(m+1)(m+2)/6, {m,0,20}]}, Table[If[MemberQ[ms, n], 0, 1], {n,0,150}]];
    Table[t=0; m=3; p=BitShiftRight[n]; n--; While[n>p, t += A014306[[n+1]]; n -= m++]; t, {n, 120}] (* G. C. Greubel, Feb 17 2022 *)
  • Sage
    nmax=120
    @CachedFunction
    def b_list(N):
        A = []
        for m in range(ceil((6*N)^(1/3))):
            A.extend([0]*(binomial(m+2, 3) - len(A)) + [1])
        return A
    A023533 = b_list(nmax+5)
    def A014306(n): return 1 - A023533[n]
    def b(n, j): return A014306(n-j+1) if ((sqrt(8*j+9) -3)/2).is_integer() else 0
    @CachedFunction
    def A024327(n): return sum( b(n, j) for j in (1..floor((n+1)/2)) )
    [A024327(n) for n in (1..nmax)] # G. C. Greubel, Feb 17 2022

Formula

a(n) = Sum_{k=1..floor((n+1)/2)} A023531(k)*A014306(n-k+1). - G. C. Greubel, Feb 17 2022

Extensions

Title corrected by Sean A. Irvine, Jun 30 2019

A024693 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023533, t = A014306.

Original entry on oeis.org

0, 1, 1, 0, 1, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 2, 3, 3, 2, 3, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 3, 4, 4, 3, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 4, 5, 5, 5, 5, 5, 5, 5, 5, 4, 5, 5, 4, 5, 5, 4
Offset: 1

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Crossrefs

Programs

  • Magma
    A023533:= func< n | Binomial(Floor((6*n-1)^(1/3)) +2, 3) ne n select 0 else 1 >;
    [(&+[A023533(k)*(1-A023533(n+1-k)): k in [1..Floor((n+1)/2)]]): n in [1..100]]; // G. C. Greubel, Jul 15 2022
    
  • Mathematica
    A023533[n_]:= If[Binomial[Floor[Surd[6*n-1, 3]] +2, 3] != n, 0, 1];
    A024693[n_]:= A024693[n]= Sum[(1-A023533[n-k+2])*A023533[k], {k,Floor[(n+1)/2]}];
    Table[A024693[n], {n,0,100}] (* G. C. Greubel, Jul 15 2022 *)
  • SageMath
    def A023533(n):
        if binomial( floor( (6*n-1)^(1/3) ) +2, 3) != n: return 0
        else: return 1
    [sum(A023533(k)*(1-A023533(n-k+1)) for k in (1..((n+1)//2))) for n in (1..100)] # G. C. Greubel, Jul 15 2022

Formula

a(n) = Sum_{k=1..floor((n+1)/2)} A023533(k)*A014306(n+1-k).
a(n) = Sum_{k=1..floor((n+1)/2)} A023533(k)*(1 - A023533(n-k+1)). - G. C. Greubel, Jul 15 2022

A023671 Convolution of A023533 and A014306.

Original entry on oeis.org

0, 1, 1, 0, 2, 2, 1, 2, 2, 1, 3, 3, 1, 3, 3, 3, 3, 3, 2, 2, 4, 4, 2, 4, 4, 4, 4, 4, 2, 4, 4, 4, 4, 4, 3, 5, 5, 3, 4, 5, 5, 5, 5, 3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 3, 5, 4, 6, 6, 4, 6, 6, 6, 6, 6, 4, 6, 6, 6, 5, 6, 6, 6, 6, 6, 4, 6, 6, 6, 6, 6, 6, 6, 6, 5, 7, 7, 5, 7, 7, 5
Offset: 1

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Programs

Formula

a(n) = Sum_{j=1..n} A023533(n-j+1)*A014306(j).
From G. C. Greubel, Jul 18 2022: (Start)
a(n) = Sum_{j=1..n} A023533(n-j+1)*(1 - A023533(j)).
a(n) = A056556(n) - A023670(n). (End)

A024890 a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = A023531, t = A014306.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 2, 2, 3, 3, 2, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 4, 3, 4, 4, 3, 4, 4, 3, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 5, 5, 6, 6, 5, 6, 6, 5, 5, 6, 6, 5, 6, 6, 6, 6, 5, 7, 7, 7, 7, 7, 6, 7, 7, 7, 7, 7, 7, 6, 7, 7, 6, 7, 7, 7, 8, 7, 8, 7, 8, 8, 8, 8, 7, 8, 7, 8, 8, 8, 7, 8, 8, 8, 8, 9, 8, 8, 9, 9, 9
Offset: 2

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Extensions

a(102) onward corrected by Sean A. Irvine, Jul 27 2019

A025126 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n-k+1), where k = floor(n/2), s = A023533, t = A014306.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 2, 3, 3, 2, 3, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 3, 4, 4, 3, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 4, 5, 5, 5, 5, 5, 5, 5, 5, 4, 5, 5, 4, 5, 5, 4, 5, 5, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6
Offset: 1

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Crossrefs

Cf. A024693. [From R. J. Mathar, Oct 23 2008]

Programs

  • Magma
    A023533:= func< n | Binomial(Floor((6*n-1)^(1/3)) +2, 3) ne n select 0 else 1 >;
    A025126:= func< n | (&+[(1-A023533(n+2-k))*A023533(k): k in [1..Floor((n+1)/2)]]) >;
    [A025126(n): n in [1..130]]; // G. C. Greubel, Sep 14 2022
    
  • Mathematica
    b[j_]:= b[j]= Sum[KroneckerDelta[j, Binomial[m+2,3]], {m,0,15}];
    A025126[n_]:= A025126[n]= Sum[(1-b[j+1])*b[n-j+1], {j, Floor[(n+2)/2], n}];
    Table[A025126[n], {n,130}] (* G. C. Greubel, Sep 14 2022 *)
  • SageMath
    @CachedFunction
    def b(j): return sum(bool(j==binomial(m+2,3)) for m in (0..15))
    @CachedFunction
    def A025126(n): return sum((1-b(j+1))*b(n-j+1) for j in (((n+2)//2)..n))
    [A025126(n) for n in (1..130)] # G. C. Greubel, Sep 14 2022

A023544 Convolution of natural numbers with A014306.

Original entry on oeis.org

0, 1, 3, 5, 8, 12, 17, 23, 30, 37, 45, 54, 64, 75, 87, 100, 114, 129, 145, 161, 178, 196, 215, 235, 256, 278, 301, 325, 350, 376, 403, 431, 460, 490, 520, 551, 583, 616, 650, 685, 721, 758, 796, 835, 875, 916, 958, 1001, 1045, 1090, 1136, 1183
Offset: 1

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A023566 Convolution of A023531 and A014306.

Original entry on oeis.org

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

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A023605 Convolution of A023532 and A014306.

Original entry on oeis.org

0, 1, 1, 1, 3, 2, 3, 5, 5, 4, 6, 7, 7, 9, 8, 9, 11, 12, 12, 12, 13, 13, 16, 16, 16, 17, 18, 19, 20, 21, 21, 22, 24, 24, 24, 26, 25, 27, 29, 28, 29, 30, 32, 33, 32, 34, 35, 36, 36, 37, 38, 39, 41, 43, 41, 41, 44, 43, 44, 46, 47, 47, 50, 50, 50, 50, 51, 53, 55, 54, 55
Offset: 1

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A023614 Convolution of Fibonacci numbers and A014306.

Original entry on oeis.org

0, 1, 2, 3, 6, 10, 17, 28, 46, 74, 121, 196, 318, 515, 834, 1350, 2185, 3536, 5722, 9258, 14981, 24240, 39222, 63463, 102686, 166150, 268837, 434988, 703826, 1138815, 1842642, 2981458, 4824101, 7805560
Offset: 0

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A023624 Convolution of Lucas numbers and A014306.

Original entry on oeis.org

0, 1, 4, 7, 12, 22, 37, 62, 102, 166, 269, 438, 710, 1151, 1864, 3018, 4885, 7906, 12794, 20702, 33497, 54202, 87702, 141907, 229612, 371522, 601137, 972662, 1573802, 2546467, 4120272, 6666742, 10787017, 17453762, 28240781, 45694544
Offset: 1

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Extensions

a(28) corrected and more terms from Sean A. Irvine, Jun 08 2019
Showing 1-10 of 38 results. Next