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 1-3 of 3 results.

A130624 Binomial transform of A101000.

Original entry on oeis.org

0, 1, 5, 12, 23, 43, 84, 169, 341, 684, 1367, 2731, 5460, 10921, 21845, 43692, 87383, 174763, 349524, 699049, 1398101, 2796204, 5592407, 11184811, 22369620, 44739241, 89478485, 178956972, 357913943, 715827883, 1431655764, 2863311529, 5726623061, 11453246124
Offset: 0

Views

Author

Paul Curtz, Jun 18 2007

Keywords

Crossrefs

Cf. A101000, A119910, A130625 (first differences), A130626 (second differences).

Programs

  • Magma
    m:=32; S:=[[0, 1, 3][(n-1) mod 3 +1]: n in [1..m]]; [&+[Binomial(i-1, k-1)*S[k]: k in [1..i]]: i in [1..m]]; /* Klaus Brockhaus, Jun 21 2007 */
    
  • Magma
    I:=[0,1,5]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+2*Self(n-3): n in [1..50]]; // Vincenzo Librandi, Nov 15 2018
  • Mathematica
    LinearRecurrence[{3,-3,2},{0,1,5},40] (* Harvey P. Dale, Mar 05 2013 *)
    RecurrenceTable[{a[0]==0, a[1]==1, a[n]==(2^n) + a[n-1] - a[n-2]}, a, {n, 50}] (* Vincenzo Librandi, Nov 15 2018 *)
  • PARI
    {m=32; v=concat([0, 1, 5], vector(m-3)); for(n=4, m, v[n]=3*v[n-1]-3*v[n-2]+2*v[n-3]); v} /* Klaus Brockhaus, Jun 21 2007 */
    

Formula

a(0)=0, a(1)=1, a(2)=5; for n>2, a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3).
a(0)=0; a(n+1) = 2*a(n) + A119910(n).
G.f.: x*(1 + 2*x)/((1 - 2*x)*(1 - x + x^2)).
a(n) = 2^n + a(n-1) - a(n-2). - Jon Maiga, Nov 14 2018

Extensions

Edited and extended by Klaus Brockhaus, Jun 21 2007

A288913 a(n) = Lucas(4*n + 3).

Original entry on oeis.org

4, 29, 199, 1364, 9349, 64079, 439204, 3010349, 20633239, 141422324, 969323029, 6643838879, 45537549124, 312119004989, 2139295485799, 14662949395604, 100501350283429, 688846502588399, 4721424167835364, 32361122672259149, 221806434537978679, 1520283919093591604
Offset: 0

Views

Author

Bruno Berselli, Jun 19 2017

Keywords

Comments

a(n) mod 4 gives A101000.

Crossrefs

Cf. A033891: fourth quadrisection of A000045.
Partial sums are in A081007 (after 0).
Positive terms of A098149, and subsequence of A001350, A002878, A016897, A093960, A068397.
Quadrisection of A000032: A056854 (first), A056914 (second), A246453 (third, without 11), this sequence (fourth).

Programs

  • Magma
    [Lucas(4*n + 3): n in [0..30]]; // G. C. Greubel, Dec 22 2017
    
  • Mathematica
    LucasL[4 Range[0, 21] + 3]
    LinearRecurrence[{7,-1}, {4,29}, 30] (* G. C. Greubel, Dec 22 2017 *)
  • PARI
    Vec((4 + x)/(1 - 7*x + x^2) + O(x^30)) \\ Colin Barker, Jun 20 2017
    
  • Python
    from sympy import lucas
    def a(n):  return lucas(4*n + 3)
    print([a(n) for n in range(22)]) # Michael S. Branicky, Apr 29 2021
  • Sage
    def L():
        x, y = -1, 4
        while True:
            yield y
            x, y = y, 7*y - x
    r = L(); [next(r) for  in (0..21)] # _Peter Luschny, Jun 20 2017
    

Formula

G.f.: (4 + x)/(1 - 7*x + x^2).
a(n) = 7*a(n-1) - a(n-2) for n>1, with a(0)=4, a(1)=29.
a(n) = ((sqrt(5) + 1)^(4*n + 3) - (sqrt(5) - 1)^(4*n + 3))/(8*16^n).
a(n) = Fibonacci(4*n+4) + Fibonacci(4*n+2).
a(n) = 4*A004187(n+1) + A004187(n).
a(n) = 5*A003482(n) + 4 = 5*A081016(n) - 1.
a(n) = A002878(2*n+1) = A093960(2*n+3) = A001350(4*n+3) = A068397(4*n+3).
a(n+1)*a(n+k) - a(n)*a(n+k+1) = 15*Fibonacci(4*k). Example: for k=6, a(n+1)*a(n+6) - a(n)*a(n+7) = 15*Fibonacci(24) = 695520.

A102002 Weighted tribonacci (1,2,4), companion to A102001.

Original entry on oeis.org

1, 7, 13, 31, 85, 199, 493, 1231, 3013, 7447, 18397, 45343, 111925, 276199, 681421, 1681519, 4149157, 10237879, 25262269, 62334655, 153810709, 379529095, 936489133, 2310790159, 5701884805, 14069421655, 34716351901, 85662734431, 211373124853, 521564001319
Offset: 1

Views

Author

Gary W. Adamson, Dec 23 2004

Keywords

Comments

a(n)/a(n-1) tends to 2.46750385...an eigenvalue of M and a root of the characteristic polynomial x^3 - x^2 - 2x - 4. A102001 is generated from [1 1 1 / 2 0 0 / 0 2 0] but has the same characteristic polynomial and recursive multipliers (1,2,4). A101000 uses the recursive multipliers (1,2,4,8).

Examples

			a(6) = 199 = 85 + 2*31 + 4*13 = a(5) + 2*a(4) + 4*a(3).
a(6) = 199 since M^6 * [1 1 1] = [85 199 493] = [a(5) a(6) a(7)].
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1,2,4}, {1,7,13}, 50] (* Harvey P. Dale, Apr 28 2012 *)
  • Sage
    from sage.combinat.sloane_functions import recur_gen3
    it = recur_gen3(1,1,1,1,2,4)
    [next(it) for i in range(32)]
    # Zerinvary Lajos, Jun 25 2008

Formula

a(n) = a(n-1) + 2*a(n-2) + 4*a(n-3), a>3. a(n) = center term in M^n * [1 1 1], where M = the 3X3 matrix [0 1 0 / 0 0 1 / 4 2 1]; M^n * [1 1 1] = [a(n-1) a(n) a(n+1)].
G.f.: -x*(4*x^2+6*x+1)/(4*x^3+2*x^2+x-1). [Harvey P. Dale, Apr 28 2012]

Extensions

More terms from Harvey P. Dale, Apr 28 2012
Showing 1-3 of 3 results.