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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A181716 a(n) = a(n-1) + a(n-2) + (-1)^n, with a(0)=0 and a(1)=1.

Original entry on oeis.org

0, 1, 2, 2, 5, 6, 12, 17, 30, 46, 77, 122, 200, 321, 522, 842, 1365, 2206, 3572, 5777, 9350, 15126, 24477, 39602, 64080, 103681, 167762, 271442, 439205, 710646, 1149852, 1860497, 3010350, 4870846, 7881197, 12752042, 20633240, 33385281, 54018522, 87403802
Offset: 0

Views

Author

Robert G. Wilson v, Nov 07 2010

Keywords

Comments

Aside from the first term, duplicate of A098600.

Crossrefs

First differences of A014217.

Programs

  • Magma
    I:=[0, 1, 2]; [n le 3 select I[n] else 2*Self(n-2)+Self(n-3): n in [1..40]]; // Vincenzo Librandi, Jan 09 2012
    
  • Magma
    [Lucas(n-1)+(-1)^n: n in [0..40]]; // G. C. Greubel, Mar 25 2024
    
  • Mathematica
    a[0]= 0; a[1]= 1; a[n_]:= a[n]= a[n-1] +a[n-2] +(-1)^n; Array[a,38,0]
    LinearRecurrence[{0,2,1},{0,1,2},40] (* Vincenzo Librandi, Jan 09 2012 *)
  • SageMath
    [lucas_number2(n-1,1,-1)+(-1)^n for n in range(41)] # G. C. Greubel, Mar 25 2024

Formula

a(n) = a(n-1) + a(n-2) + (-1)^n.
a(n) = 2*a(n-2) + a(n-3).
a(n) - A000045(n) = A008346(n-2).
G.f.: x*(1+2*x)/(1-2*x^2-x^3). - Colin Barker, Jan 09 2012
a(n) = A000032(n-1) + (-1)^n. - G. C. Greubel, Mar 25 2024
E.g.f.: exp(x/2)*(sqrt(5)*sinh(sqrt(5)*x/2) - cosh(sqrt(5)*x/2)) + exp(-x). - Stefano Spezia, Jun 18 2024

A141169 Triangle of Fibonacci numbers, read by rows: T(n,k) = A000045(k), 0<=k<=n.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 1, 2, 0, 1, 1, 2, 3, 0, 1, 1, 2, 3, 5, 0, 1, 1, 2, 3, 5, 8, 0, 1, 1, 2, 3, 5, 8, 13, 0, 1, 1, 2, 3, 5, 8, 13, 21, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 0, 1, 1, 2, 3, 5, 8, 13, 21
Offset: 0

Views

Author

Reinhard Zumkeller, Mar 21 2011

Keywords

Comments

T(n,0) = A000004(n); T(n,n) = A000045(n);
central terms: T(2*n,n) = A000045(n);
sums of rows: Sum(T(n,k): 0<=k<=n) = A000071(n+2);
alternating sums of rows: Sum(T(n,k)*(-1)^k: 0<=k<=n) = A119282(n);
T(n,k) + T(n,n-k) = A094570(n,k).

Crossrefs

Programs

  • Haskell
    import Data.List (inits)
    a141169 n k = a141169_tabl !! n !! k
    a141169_row n = a141169_tabl !! n
    a141169_tabl = tail $ inits a000045_list
    a141169_list = concat $ a141169_tabl
    -- Reinhard Zumkeller, Aug 24 2015, Mar 21 2011

A082987 a(n) = Sum_{k=0..n} 3^k*F(k) where F(k) is the k-th Fibonacci number.

Original entry on oeis.org

0, 3, 12, 66, 309, 1524, 7356, 35787, 173568, 842790, 4090485, 19856568, 96384072, 467861331, 2271040644, 11023873914, 53510987541, 259747827852, 1260842371428, 6120257564955, 29708354037720, 144207380197758
Offset: 0

Views

Author

Benoit Cloitre, May 29 2003

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{4,6,-9},{0,3,12},30] (* Harvey P. Dale, Feb 03 2019 *)
  • PARI
    a(n)=if(n<0,0,sum(k=0,n,fibonacci(k)*3^k))

Formula

a(0)=0, a(1)=3, a(2)=12, a(n)=4a(n-1)+6a(n-2)-9a(n-3).
G.f.: 3*x / ((x-1)*(9*x^2+3*x-1)). - Colin Barker, Jun 26 2013

Extensions

Offset changed to 0 by Seiichi Manyama, Oct 03 2023

A082988 a(n) = Sum_{k=0..n} 4^k*F(k) where F(k) is the k-th Fibonacci number.

Original entry on oeis.org

0, 4, 20, 148, 916, 6036, 38804, 251796, 1628052, 10540948, 68212628, 441505684, 2857424788, 18493790100, 119693957012, 774676469652, 5013809190804, 32450060277652, 210021188163476, 1359285717096340, 8797481879000980
Offset: 0

Views

Author

Benoit Cloitre, May 29 2003

Keywords

Comments

More generally for any complex number z, the sequence a(n) = Sum_{k=0..n} z^k*F(k) satisfies the recurrence: a(0) = 0, a(1) = z, a(2) = z(z+1), for n > 2 a(n) = (z+1)*a(n-1)+z*(z-1)*a(n-2)-z^2*a(n-3).

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5, 12, -16}, {0, 4, 20}, 21] (* Amiram Eldar, Apr 29 2025 *)
  • PARI
    a(n)=if(n<0,0,sum(k=0,n,fibonacci(k)*4^k));

Formula

a(0) = 0, a(1) = 4, a(2) = 20, a(n) = 5a(n-1)+12a(n-2)-16a(n-3).
O.g.f.: 4*x/((x-1)*(16*x^2+4*x-1)). - R. J. Mathar, Dec 05 2007

A117724 Triangle T(n,k) = coefficient [x^n] of x^2/(1-(k+1)*x^2-x^3) for row n, and columns k = 0..n, read by rows.

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 2, 3, 4, 5, 1, 1, 1, 1, 1, 1, 1, 4, 9, 16, 25, 36, 49, 2, 4, 6, 8, 10, 12, 14, 16, 2, 9, 28, 65, 126, 217, 344, 513, 730, 3, 12, 27, 48, 75, 108, 147, 192, 243, 300, 4, 22, 90, 268, 640, 1314, 2422, 4120, 6588, 10030, 14674
Offset: 0

Views

Author

Roger L. Bagula, Apr 13 2006

Keywords

Examples

			The table starts:
  0;
  0,  0;
  1,  1,  1;
  0,  0,  0,  0;
  1,  2,  3,  4,   5;
  1,  1,  1,  1,   1,   1;
  1,  4,  9, 16,  25,  36,  49;
  2,  4,  6,  8,  10,  12,  14,  16;
  2,  9, 28, 65, 126, 217, 344, 513, 730;
  3, 12, 27, 48,  75, 108, 147, 192, 243, 300;
		

Crossrefs

Programs

  • Magma
    m:=12;
    R:=PowerSeriesRing(Integers(), m+2);
    A117724:= func< n, k | Coefficient(R!( x^2/(1-(k+1)*x^2-x^3) ), n) >;
    [A117724(n, k): k in [0..n], n in [0..m]]; // G. C. Greubel, Jul 23 2023
    
  • Maple
    t:=taylor(x^2/(1-(k+1)*x^2-x^3), x, 15):
    seq(seq(coeff(t,x,n), k=0..n),n=0..12); # Nathaniel Johnston, Apr 27 2011
  • Mathematica
    T[n_, k_]:= T[n, k]= Coefficient[Series[x^2/(1-(k+1)*x^2-x^3), {x,0,n+ 2}], x, n];
    Table[T[n,k], {n,0,12}, {k,0,n}]//Flatten
  • SageMath
    def A117724(n, k):
        P. = PowerSeriesRing(QQ)
        return P( x^2/(1-(k+1)*x^2-x^3) ).list()[n]
    flatten([[A117724(n, k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Jul 23 2023

Formula

T(n,k) = coefficient [x^n] ( x^2/(1-(k+1)*x^2-x^3) ).
T(n, 0) = A000931(n+1).
T(n, 1) = A008346(n-2) = (-1)^(n-1)*A119282(n-1).
T(n, 2) = A052931(n-2).

Extensions

Sign in definition corrected, offset set to -1 by Assoc. Eds. of the OEIS, Jun 15 2010
Edited by G. C. Greubel, Jul 23 2023
Previous Showing 11-15 of 15 results.