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 1-4 of 4 results.

A346513 a(n) = Fibonacci(n+1)^3 - Fibonacci(n)^3.

Original entry on oeis.org

1, 0, 7, 19, 98, 387, 1685, 7064, 30043, 127071, 538594, 2281015, 9663353, 40933296, 173398367, 734523803, 3111498370, 13180509531, 55833549037, 236514685384, 1001892323411, 4244083925895, 17978228112962, 76156996238639, 322606213292593, 1366581849044832
Offset: 0

Views

Author

Lamine Ngom, Jul 21 2021

Keywords

Comments

The version related to sum of consecutive Fibonacci numbers cubed is given by A110224.
a(n+1) is divisible by Fibonacci(n). The related quotient sequence is provided by A061646, from its 3rd term.

Crossrefs

Cf. A056570 (partial sums).

Programs

  • Mathematica
    Differences[Fibonacci[Range[0, 26]]^3] (* Amiram Eldar, Jul 22 2021 *)
  • PARI
    a(n) = fibonacci(n+1)^3 - fibonacci(n)^3; \\ Michel Marcus, Jul 22 2021

Formula

a(n) = F(n-1)*(2*F(n+1)^2+(-1)^(n+1)), n>0.
a(n) = F(n-1)*A061646(n+1).
G.f.: (x-1)*(x^2+2*x-1)/((x^2+4*x-1)*(x^2-x-1)). - Alois P. Heinz, Jul 21 2021
For n >= 2, a(n) is the numerator of the continued fraction [1,...,1, 3 ,1,...,1, 2 ,1,...,1] with three runs of 1's each of length n-2. For example, a(5)=387 which is the numerator of the continued fraction [1,1,1, 3 ,1,1,1, 2 ,1,1,1]. - Greg Dresden, Jan 01 2022

A350473 a(n) = Fibonacci(n+1)^3 - Fibonacci(n-1)^3.

Original entry on oeis.org

0, 1, 7, 26, 117, 485, 2072, 8749, 37107, 157114, 665665, 2819609, 11944368, 50596649, 214331663, 907922170, 3846022173, 16292007901, 69014058568, 292348234421, 1238407008795, 5245976249306, 22222312038857, 94135224351601, 398763209531232, 1689188062337425
Offset: 0

Views

Author

Greg Dresden, Jan 01 2022

Keywords

Comments

See A346513 for Fibonacci(n+1)^3 - Fibonacci(n)^3.

Crossrefs

Programs

  • Mathematica
    Differences[Fibonacci[Range[-1, 26]]^3, 1, 2]
  • Python
    from sympy import fibonacci
    def A350473(n): return fibonacci(n+1)**3-fibonacci(n-1)**3 # Chai Wah Wu, Jan 05 2022

Formula

a(n) = 3*a(n-1) + 6*a(n-2) - 3*a(n-3) - a(n-4).
G.f.: x*(1 + 4*x - x^2)/(1 - 3*x - 6*x^2 + 3*x^3 + x^4).
a(n) = (4/5)*Fibonacci(3*n) + (-1)^(n)*(3/5)*Fibonacci(n).
a(n) is the numerator of the continued fraction [1,...,1, 2 ,1,...,1, 2 ,1,1,...,1] with the first two runs of 1's of length n-2 and the last run of length n-1. For example, a(4)=117 which is the numerator of the continued fraction [1,1, 2 ,1,1, 2 ,1,1,1].

A226958 a(n) = Fibonacci(n-2)*Fibonacci(n)*Fibonacci(n+2).

Original entry on oeis.org

2, 0, 10, 24, 130, 504, 2210, 9240, 39338, 166320, 705058, 2985840, 12649570, 53582256, 226981610, 961503816, 4073004770, 17253510120, 73087065922, 309601740360, 1311494081482, 5555577978720, 23533806138050, 99690802301664, 422297015715650, 1788878864564064, 7577812474943050
Offset: 1

Views

Author

Ron Knott, Jun 27 2013

Keywords

Examples

			a(3) = F(1)*F(3)*F(5) = 1*2*5 = 10.
		

Crossrefs

Cf. A000045 (Fibonacci numbers), A000032 (Lucas numbers).
Products of 3 Fibonaccis: A065563, A056570, A220362, A110224.

Programs

  • Mathematica
    Table[Fibonacci[n - 2] Fibonacci[n] Fibonacci[n + 2], {n, 1, 20}]
    LinearRecurrence[{3,6,-3,-1},{2,0,10,24},30] (* Harvey P. Dale, Apr 10 2022 *)
    Join[{2},#[[1]]#[[3]]#[[5]]&/@Partition[Fibonacci[Range[0,40]],5,1]] (* Harvey P. Dale, May 20 2025 *)
  • PARI
    a(n)=fibonacci(n-2)*fibonacci(n)*fibonacci(n+2); \\ Joerg Arndt, Jul 07 2013

Formula

a(n) = 3*a(n-1) + 6*a(n-2) - 3*a(n-3) - a(n-4).
G.f.: 2*(1-3*x-x^2)/(1-3*x-6*x^2+3*x^3+x^4).
a(n) = Lucas(n-1)*Fibonacci(n+2) = Fibonacci(n-2)*Lucas(n+1).
a(n) = (1/5)*(Fibonacci(3*n)-8*(-1)^n*Fibonacci(n)). - Ehren Metcalfe, Mar 26 2016
For n >= 3, a(n) is the numerator of the continued fraction [1,..,1, 3 ,1,..,1, 3 ,1,..,1] with three runs of 1's each of length n-3 and each separated by a single 3. For example, a(5)=130 which is the numerator of the continued fraction [1,1, 3 ,1,1, 3 ,1,1]. - Greg Dresden, Jan 01 2022

Extensions

More terms from Joerg Arndt, Jul 07 2013

A226976 Fibonacci(n)^3 + Fibonacci(n+2)^3.

Original entry on oeis.org

1, 9, 28, 133, 539, 2322, 9773, 41501, 175636, 744273, 3152359, 13354306, 56568617, 239630337, 1015087436, 4299984173, 18215017507, 77160064914, 326855259829, 1384581132277, 5865179743556, 24845300179929, 105246380344463, 445830821750018, 1888569667033489
Offset: 0

Views

Author

Ron Knott, Jun 27 2013

Keywords

Examples

			a(2) = Fibonacci(2)^3 + Fibonacci(4)^3 = 1^3 + 2^3 = 9
		

Crossrefs

Cf. A000045 (Fibonacci), A056570 (Fibonacci^3).
Cf. A110224 (Fib(n)^3 + Fib(n+1)^3).

Programs

  • Mathematica
    Table[Fibonacci[n]^3 + Fibonacci[n+2]^3,{n,0,50}]
    #[[1]]+#[[3]]&/@Partition[Fibonacci[Range[0,30]]^3,3,1] (* or *) LinearRecurrence[{3,6,-3,-1},{1,9,28,133},30] (* Harvey P. Dale, Jun 30 2025 *)
  • PARI
    a(n) = fibonacci(n)^3+fibonacci(n+2)^3; \\ Joerg Arndt, Jul 07 2013

Formula

a(n) = 3a(n-1)+6a(n-2)-3a(n-3)-a(n-4)
G.f.: (1+6x-5x^2-2x^3)/(1-3x-6x^2+3x^3+x^4)= (2x^2+7x+1)(1-x)/((x^2-x-1)(x^2+4x-1))
Showing 1-4 of 4 results.