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.

A116470 All distinct Fibonacci and Lucas numbers.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 8, 11, 13, 18, 21, 29, 34, 47, 55, 76, 89, 123, 144, 199, 233, 322, 377, 521, 610, 843, 987, 1364, 1597, 2207, 2584, 3571, 4181, 5778, 6765, 9349, 10946, 15127, 17711, 24476, 28657, 39603, 46368, 64079, 75025, 103682, 121393, 167761
Offset: 0

Views

Author

Alexander Adamchuk, Aug 13 2006

Keywords

Comments

See A115339 for an essentially identical sequence.

Crossrefs

Union of A000045 and A000032.
Cf. A288219 (even bisection).

Programs

  • Haskell
    import Data.List (transpose)
    a116470 n = a116470_list !! n
    a116470_list = 0 : 1 : 2 : concat
                   (transpose [drop 4 a000045_list, drop 3 a000032_list])
    -- Reinhard Zumkeller, Aug 03 2013
    
  • Maple
    FL := (n, a, b) -> hypergeom([a - n/2, b - n/2], [1 - n], -4):
    a := n -> `if`(n < 3, n, FL((n + 2 + 3*irem(n, 2))/2, irem(n, 2), 1/2)):
    seq(simplify(a(n)), n=0..52); # Peter Luschny, Sep 03 2019
  • Mathematica
    CoefficientList[Series[-x*(x^2 + x + 1)*(x^3 + x + 1)/(-1 + x^4 + x^2), {x, 0, 50}], x] (* G. C. Greubel, Dec 21 2017 *)
    With[{nn=50},Select[Union[Join[LucasL[Range[0,nn]],Fibonacci[Range[0,nn]]]],#<=200000&]] (* Harvey P. Dale, Jul 05 2019 *)
  • PARI
    my(x='x+O('x^50)); concat([0], Vec(-x*(x^2+x+1)*(x^3+x+1)/( -1+x^4 +x^2))) \\ G. C. Greubel, Dec 21 2017
    
  • PARI
    a(n)=if(n<6, n, if(n%2, fibonacci(n\2+3), fibonacci(n\2)+fibonacci(n\2+2))) \\ Charles R Greathouse IV, Oct 14 2021

Formula

a(0) = 0, a(1) = 1, a(2) = 2, a(3) = 3, a(4) = 4, a(5) = 5, a(6) = 7, a(n) = a(n-2) + a(n-4) for n>6.
a(2*n) = Lucas(n+1) = Fibonacci(n) + Fibonacci(n+2) for n>1.
a(2*n+1) = Fibonacci(n+3) for n>2.
G.f.: -x*(x^2+x+1)*(x^3+x+1)/(-1+x^4+x^2). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 12 2009
a(n) = FL((n + 2 + 3*(n mod 2))/2, n mod 2, 1/2) for n >= 3. Here FL(n, a, b) = hypergeom([a - n/2, b - n/2], [1 - n], -4). - Peter Luschny, Sep 03 2019

A180236 a(n) = a(n-2)+a(n-4); a(1)=a(4)=101, a(2)=a(3)=10.

Original entry on oeis.org

101, 10, 10, 101, 111, 111, 121, 212, 232, 323, 353, 535, 585, 858, 938, 1393, 1523, 2251, 2461, 3644, 3984, 5895, 6445, 9539, 10429, 15434, 16874, 24973, 27303, 40407, 44177, 65380, 71480, 105787, 115657, 171167, 187137, 276954, 302794, 448121, 489931
Offset: 1

Views

Author

Mark Dols, Aug 18 2010

Keywords

Comments

Generalization of A115339.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0,1,0,1},{101,10,10,101},50] (* Paolo Xausa, Jan 04 2024 *)
  • PARI
    Vec(-x*(91*x^3-91*x^2+10*x+101)/(x^4+x^2-1) + O(x^100)) \\ Colin Barker, Oct 03 2015
    
  • PARI
    a(n) = if(n==1||n==4, 101, if(n==2||n==3, 10, a(n-2)+a(n-4))); \\ Altug Alkan, Oct 03 2015

Formula

G.f.: -x*(91*x^3-91*x^2+10*x+101) / (x^4+x^2-1). Colin Barker, Oct 03 2015

A236144 a(n) = F(floor( (n+3)/2 )) * L(floor( (n+2)/2 )) where F=Fibonacci and L=Lucas numbers.

Original entry on oeis.org

2, 2, 1, 2, 6, 9, 12, 20, 35, 56, 88, 143, 234, 378, 609, 986, 1598, 2585, 4180, 6764, 10947, 17712, 28656, 46367, 75026, 121394, 196417, 317810, 514230, 832041, 1346268, 2178308, 3524579, 5702888, 9227464, 14930351, 24157818, 39088170, 63245985, 102334154
Offset: 0

Views

Author

Michael Somos, Jan 19 2014

Keywords

Examples

			G.f. = 2 + 2*x + x^2 + 2*x^3 + 6*x^4 + 9*x^5 + 12*x^6 + 20*x^7 + 35*x^8 + ...
		

Crossrefs

Programs

  • Magma
    m:=60; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(2-x^2-x^3)/(1-x-x^3-x^4)); // G. C. Greubel, Aug 07 2018
  • Mathematica
    a[ n_] := Fibonacci[ Quotient[ n + 3, 2]] LucasL[ Quotient[ n, 2]];
    CoefficientList[Series[(2-x^2-x^3)/(1-x-x^3-x^4), {x, 0, 60}], x] (* G. C. Greubel, Aug 07 2018 *)
  • PARI
    {a(n) = fibonacci( (n+3)\2 ) * (fibonacci( n\2+1 ) + fibonacci( n\2-1 ))};
    
  • PARI
    x='x+O('x^60); Vec((2-x^2-x^3)/(1-x-x^3-x^4)) \\ G. C. Greubel, Aug 07 2018
    

Formula

G.f.: (2 - x^2 - x^3) / (1 - x - x^3 - x^4) = (1 - x) * (2 + 2*x + x^2) / ((1 + x^2) * (1 - x - x^2)).
a(n) = a(n-1) + a(n-3) + a(n-4) for all n in Z.
0 = a(n)*a(n+2) + a(n+1)*(+a(n+2) -a(n+3)) for all n in Z.
a(n) = A115008(n+2) - A115008(n+1).
a(n) = A115339(n) * A115339(n-1).
a(2*n - 1) = F(n+1) * L(n-1) = A128535(n+1). a(2*n) = F(n+1) * L(n) = A128534(n+1).
a(n) = A000045(n+1)+A057077(n). - R. J. Mathar, Sep 24 2021
Showing 1-3 of 3 results.