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 1-7 of 7 results.

A099036 a(n) = 2^n - Fibonacci(n).

Original entry on oeis.org

1, 1, 3, 6, 13, 27, 56, 115, 235, 478, 969, 1959, 3952, 7959, 16007, 32158, 64549, 129475, 259560, 520107, 1041811, 2086206, 4176593, 8359951, 16730848, 33479407, 66987471, 134021310, 268117645, 536356683, 1072909784, 2146137379, 4292788987, 8586410014
Offset: 0

Views

Author

Paul Barry, Sep 23 2004

Keywords

Comments

Binomial transform of (-1)^n*A000045(n) + 1 = (-1)^n*A008346(n).
Number of compositions of n+1 that contain 1 as a part. - Vladeta Jovovic, Sep 26 2004
Generated from iterates of M * [1,1,1,...], where M = a tridiagonal matrix with [0,1,1,1,...] as the main diagonal, [1,1,1,...] as the superdiagonal and [1,0,0,0,...] as the subdiagonal. - Gary W. Adamson, Jan 05 2009
Starting with offset 1, generated from iterates of M * [1,1,1,...], M*ANS -> M*ANS,...; where M = = a tridiagonal matrix with (0,1,1,1,...) in the main diagonal, (1,1,1,...) in the superdiagonal and (1,0,0,0,...) in the subdiagonal. - Gary W. Adamson, Jan 04 2009
An elephant sequence, see A175655. For the central square 24 A[5] vectors, with decimal values between 11 and 416, lead to this sequence (without the first leading 1). For the corner squares these vectors lead to the companion sequence A027934 (without the leading 0). - Johannes W. Meijer, Aug 15 2010
Number of fixed points in all compositions of n+1. - Alois P. Heinz, Jun 18 2020

Crossrefs

Programs

Formula

G.f.: (1 - x)^2/((1 - 2*x)*(1 - x - x^2)).
a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3).
a(n) = A101220(1,2,n+1) - A101220(1,2,n). - Ross La Haye, Aug 05 2005
a(n) = A000079(n+1) - A117591(n) = A117591(n) - 2 * A000045(n). - Reinhard Zumkeller, Aug 15 2013
a(n) = Sum_{t_1+2*t_2+...+n*t_n = n} multinomial(1+t_1+t_2+...+t_n, 1+t_1, t_2, ..., t_n). - Mircea Merca, Oct 09 2013
a(n) = Sum_{k=0..A003056(n+1)} k * A238350(n+1,k). - Alois P. Heinz, Jun 18 2020
E.g.f.: cosh(2*x) + sinh(2*x) - 2*exp(x/2)*sinh(sqrt(5)*x/2)/sqrt(5). - Stefano Spezia, Jan 31 2023

Extensions

More terms from Ross La Haye, Aug 05 2005

A074824 Numbers k such that 2^k + Fibonacci(k) is prime.

Original entry on oeis.org

1, 2, 4, 5, 8, 11, 16, 19, 44, 88, 224, 349, 520, 1187, 2044, 2636, 2645, 3994, 6851, 12016, 16304, 31388, 54296, 56608, 100700, 134387
Offset: 1

Views

Author

Robert G. Wilson v, Sep 06 2002

Keywords

Comments

2^(3n) + Fibonacci(3n) is even if n>0.

Crossrefs

Programs

  • Mathematica
    Do[ If[ PrimeQ[ 2^n + Fibonacci[n]], Print[n]], {n, 1, 5000}]
  • PARI
    is(n)=ispseudoprime(fibonacci(n)+2^n) \\ Charles R Greathouse IV, May 22 2017

Extensions

a(19)-a(21) from Ryan Propper, Aug 30 2005
a(22) from Amiram Eldar, May 10 2022
a(23)-a(24) from Michael S. Branicky, May 15 2023
a(25)-a(26) from Michael S. Branicky, Oct 23 2024

A212262 a(n) = 3^n + Fibonacci(n).

Original entry on oeis.org

1, 4, 10, 29, 84, 248, 737, 2200, 6582, 19717, 59104, 177236, 531585, 1594556, 4783346, 14349517, 43047708, 129141760, 387423073, 1162265648, 3486791166, 10460364149, 31381077320, 94143207484, 282429582849, 847288684468, 2541865949722, 7625597681405
Offset: 0

Views

Author

Bruno Berselli, May 08 2012

Keywords

Crossrefs

Programs

  • Magma
    [3^n+Fibonacci(n): n in [0..27]];
    
  • Mathematica
    Table[3^n + Fibonacci[n], {n, 0, 27}]
  • PARI
    for(n=0, 27, print1(3^n+fibonacci(n)", "));
    
  • Sage
    [3^n +fibonacci(n) for n in (0..30)] # G. C. Greubel, Jul 05 2021

Formula

G.f.: (1-2*x)*(1+2*x)/((1-3*x)*(1-x-x^2)).

A131375 A007318 + A046854 - A049310.

Original entry on oeis.org

1, 2, 1, 1, 3, 1, 2, 3, 4, 1, 1, 6, 6, 5, 1, 2, 5, 13, 10, 6, 1, 1, 9, 15, 24, 15, 7, 1, 2, 7, 27, 35, 40, 21, 8, 1, 1, 12, 28, 66, 70, 62, 28, 9, 1, 2, 9, 46, 84, 141, 126, 91, 36, 10, 1
Offset: 0

Views

Author

Gary W. Adamson, Jul 04 2007

Keywords

Comments

Row sums = A117591: (1, 3, 5, 10, 19, 37, 72,...).

Examples

			First few rows of the triangle are:
1;
2, 1;
1, 3, 1;
2, 3, 4, 1;
1, 6, 6, 5, 1;
2, 5, 13, 10, 6, 1;
1, 9, 15, 24, 15, 7, 1;
...
		

Crossrefs

Formula

A007318 + A046854 - A049310 as infinite lower triangular matrices.

A131376 Triangle read by rows: T(n,k) = A007318(n,k) + A065941(n,k) - A168561(n,k).

Original entry on oeis.org

1, 2, 1, 1, 3, 1, 2, 2, 5, 1, 1, 5, 6, 6, 1, 2, 3, 14, 9, 8, 1, 1, 7, 14, 24, 16, 9, 1, 2, 4, 27, 30, 45, 21, 11, 1, 1, 9, 25, 62, 70, 66, 31, 12, 1, 2, 5, 44, 71, 147, 120, 104, 38, 14, 1, 1, 11, 39, 128, 203, 273, 217, 140, 51, 15, 1, 2, 6, 65, 139, 366, 434, 518, 329, 200, 60, 17, 1
Offset: 0

Views

Author

Gary W. Adamson, Jul 04 2007

Keywords

Comments

The old definition was: A007318 + A065941 - A049310. - N. J. A. Sloane, Aug 09 2019
Row sums = A117591: (1, 3, 5, 10, 19, 37, 72, ...).

Examples

			First few rows of the triangle are:
  1;
  2, 1;
  1, 3, 1;
  2, 2, 5, 1;
  1, 5, 6, 6, 1;
  2, 3, 14, 9, 8, 1;
  1, 7, 14, 24, 16, 9, 1;
  ...
		

Crossrefs

Programs

  • Mathematica
    Table[Binomial[n, k] + Binomial[n - Floor[(k+1)/2], Floor[k/2]] - If[EvenQ[n+k], Binomial[(n+k)/2, k], 0], {n, 0, 11}, {k, 0, n}] // Flatten  (* Amiram Eldar, May 31 2025 *)

Extensions

The old definition of A131376 did not match its data, as Michel Marcus pointed out. The definition has been corrected here, keeping the data. The old definition with corrected data is now A309213. - N. J. A. Sloane, Aug 09 2019
More terms from Amiram Eldar, May 31 2025

A309213 A007318 + A065941 - A049310.

Original entry on oeis.org

1, 2, 1, 3, 3, 1, 2, 6, 5, 1, 1, 5, 12, 6, 1, 2, 3, 14, 17, 8, 1, 3, 7, 14, 24, 26, 9, 1, 2, 12, 27, 30, 45, 33, 11, 1, 1, 9, 45, 62, 70, 66, 45, 12, 1, 2, 5, 44, 111, 147, 120, 104, 54, 14, 1, 3, 11, 39, 128, 273, 273, 217, 140, 69, 15, 1, 2, 18, 65, 139, 366, 546, 518, 329, 200, 80, 17, 1
Offset: 0

Views

Author

Gary W. Adamson, Jul 04 2007

Keywords

Comments

Row sums = 1, 3, 7, 14, 25, 45, 85, ... (This is probably a new sequence and should be added to the OEIS.) - N. J. A. Sloane, Aug 09 2019

Examples

			First few rows of the triangle are:
1,
2, 1,
3, 3, 1,
2, 6, 5, 1,
1, 5, 12, 6, 1,
2, 3, 14, 17, 8, 1,
3, 7, 14, 24, 26, 9, 1,
...
		

Crossrefs

Programs

  • PARI
    T007318(n, k) = binomial(n, k);
    T065941(n, k) = binomial(n - (k+1)\2, k\2);
    T049310(n, k) = if ((n+k)%2, 0, (-1)^((n+k)/2 + k) * binomial((n+k)/2, k));
    T(n, k) = T007318(n, k) + T065941(n, k) - T049310(n, k); \\ Michel Marcus, Apr 28 2014

Formula

A007318 + A065941 - A168561 as infinite lower triangular matrices.

Extensions

The old definition of A131376 did not match the data, as Michel Marcus pointed out. The definition there has been corrected, keeping the old data. The present sequence uses the old definition with corrected data from Michel Marcus. - N. J. A. Sloane, Aug 09 2019
More terms from Jinyuan Wang, Aug 29 2019

A101353 a(n) = Sum_{k=0..n} (2^k + Fibonacci(k)).

Original entry on oeis.org

1, 4, 9, 19, 38, 75, 147, 288, 565, 1111, 2190, 4327, 8567, 16992, 33753, 67131, 133654, 266323, 531051, 1059520, 2114861, 4222959, 8434974, 16852239, 33675823, 67305280, 134535537, 268949683, 537702950, 1075088091, 2149661955, 4298491872, 8595637477
Offset: 0

Views

Author

Jorge Coveiro, Dec 25 2004

Keywords

Crossrefs

Cf. A117591 (first differences). - R. J. Mathar, Feb 06 2010

Programs

  • Maple
    seq(sum(2^x+fibonacci(x),x=0..a),a=0..30);
  • Mathematica
    Accumulate[Table[2^k+Fibonacci[k],{k,0,40}]] (* or *) LinearRecurrence[{4,-4,-1,2},{1,4,9,19},40] (* Harvey P. Dale, Aug 17 2025 *)
  • PARI
    Vec((1-3*x^2)/((1-x)*(2*x-1)*(x^2+x-1)) + O(x^40)) \\ Colin Barker, Nov 03 2016

Formula

Fibonacci(n+2) + 2^(n+1) + 2. - Ralf Stephan, May 16 2007
a(n)= 4*a(n-1) -4*a(n-2) -a(n-3) +2*a(n-4). G.f.: (1-3*x^2)/((1-x) * (2*x-1) * (x^2+x-1)). - R. J. Mathar, Feb 06 2010
a(n) = (-2+2^(1+n)+(2^(-1-n)*((1-sqrt(5))^n*(-3+sqrt(5))+(1+sqrt(5))^n*(3+sqrt(5))))/sqrt(5)). - Colin Barker, Nov 03 2016
Showing 1-7 of 7 results.