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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A376647 a(n) = Sum_{k=0..floor(n/3)} binomial(floor(k/2),n-3*k).

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 2, 1, 1, 2, 1, 1, 3, 3, 2, 3, 3, 2, 4, 6, 5, 5, 6, 5, 6, 10, 11, 10, 11, 11, 11, 16, 21, 21, 21, 22, 22, 27, 37, 42, 42, 43, 44, 49, 64, 79, 84, 85, 87, 93, 113, 143, 163, 169, 172, 180, 206, 256, 306, 332, 341, 352, 386, 462, 562
Offset: 0

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Author

Seiichi Manyama, Oct 01 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\3, binomial(k\2, n-3*k));
    
  • PARI
    my(N=80, x='x+O('x^N)); Vec((1+x^3)/(1-x^6-x^7))

Formula

G.f.: (1-x^6)/((1-x^3) * (1-x^6-x^7)) = (1+x^3)/(1-x^6-x^7).
a(n) = a(n-6) + a(n-7).
a(n) = A017847(n) + A017847(n-3).

A376648 a(n) = Sum_{k=0..floor(n/4)} binomial(floor(k/2),n-4*k).

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 1, 2, 1, 0, 1, 3, 3, 1, 1, 3, 3, 1, 1, 4, 6, 4, 2, 4, 6, 4, 2, 5, 10, 10, 6, 6, 10, 10, 6, 7, 15, 20, 16, 12, 16, 20, 16, 13, 22, 35, 36, 28, 28, 36, 36, 29, 35, 57, 71, 64, 56, 64, 72, 65, 64, 92, 128, 135
Offset: 0

Views

Author

Seiichi Manyama, Oct 01 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\4, binomial(k\2, n-4*k));
    
  • PARI
    my(N=80, x='x+O('x^N)); Vec((1+x^4)/(1-x^8-x^9))

Formula

G.f.: (1-x^8)/((1-x^4) * (1-x^8-x^9)) = (1+x^4)/(1-x^8-x^9).
a(n) = a(n-8) + a(n-9).
a(n) = A017867(n) + A017867(n-4).

A276275 Padovan like sequence: a(n) = a(n-2) + a(n-3) for n>3, a(1)=2, a(2)=2, a(3)=0.

Original entry on oeis.org

2, 2, 0, 4, 2, 4, 6, 6, 10, 12, 16, 22, 28, 38, 50, 66, 88, 116, 154, 204, 270, 358, 474, 628, 832, 1102, 1460, 1934, 2562, 3394, 4496, 5956, 7890, 10452, 13846, 18342, 24298, 32188, 42640, 56486, 74828, 99126, 131314, 173954, 230440, 305268, 404394, 535708
Offset: 1

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Author

Nicolas Bègue, Aug 26 2016

Keywords

Comments

Obtained from Padovan Spiral number (A134816) modulo 3 reduction periodic sequence 1112201210010, 111 112 122 220 ... fourth initialization values 220, it satisfies the same recurrence a(n) = a(n-2) + a(n-3).

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[n] == a[n - 2] + a[n - 3], a[1] == 2, a[2] == 2, a[3] == 0}, a, {n, 1, 48}] (* or *) CoefficientList[Series[2 x (1 + x - x^2)/(1 - x^2 - x^3), {x, 0, 47}], x] (* Michael De Vlieger, Sep 02 2016 *)
    LinearRecurrence[{0,1,1},{2,2,0},60] (* Harvey P. Dale, Jan 27 2023 *)

Formula

G.f.: 2*x*(1 + x - x^2)/(1 - x^2 - x^3).
a(n) = A134816(n) + A007307(n-3) for n>=4.
a(n) = 2*A084338(n-3) for n>=4.
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