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.

A056570 Third power of Fibonacci numbers (A000045).

Original entry on oeis.org

0, 1, 1, 8, 27, 125, 512, 2197, 9261, 39304, 166375, 704969, 2985984, 12649337, 53582633, 226981000, 961504803, 4073003173, 17253512704, 73087061741, 309601747125, 1311494070536, 5555577996431, 23533806109393, 99690802348032, 422297015640625
Offset: 0

Views

Author

Wolfdieter Lang, Jul 10 2000

Keywords

Comments

Divisibility sequence; that is, if n divides m, then a(n) divides a(m).
In general, cubing the terms of a Horadam sequence with signature (c,d) will result in a fourth-order recurrence with signature (c^3+2*c*d, c^4*d+3*(c*d)^2+2*d^3, -(c*d)^3-2*c*d^4, -d^6). - Gary Detlefs, Nov 12 2021
a(n+1) is the number of tilings of an n-board (a board with dimensions n X 1) using (1/3,2/3)-fences and third-squares (1/3 X 1 pieces, always placed so that the shorter sides are horizontal). A (w,g)-fence is a tile composed of two w X 1 pieces separated by a gap of width g. a(n+1) also equals the number of tilings of an n-board using (1/6,1/3)-fences and (1/6,5/6)-fences. - Michael A. Allen, Jan 11 2022

Examples

			a(4) = 27 because the fourth Fibonacci number is 3 and 3^3 = 27.
a(5) = 125 because the fifth Fibonacci number is 5 and 5^3 = 125.
		

References

  • D. E. Knuth, The Art of Computer Programming. Addison-Wesley, Reading, MA, 1969, Vol. 1, p. 85, (exercise 1.2.8. Nr. 30) and p. 492 (solution).

Crossrefs

Cf. A346513 (first differences), A005968 (partial sums).
Third row of array A103323.

Programs

Formula

a(n) = A000045(n)^3.
G.f.: x*p(3, x)/q(3, x) with p(3, x) = Sum_{m=0..2} A056588(2, m)*x^m = 1 -2*x -x^2 and q(3, x) = Sum_{m=0..4} A055870(4, m)*x^m = 1 -3*x -6*x^2 +3*x^3 +x^4 = (1+x-x^2)*(1-4*x-x^2) (factorization deduced from Riordan result).
Recursion (cf. Knuth's exercise): 1*a(n) -3*a(n-1) -6*a(n-2) +3*a(n-3) +1*a(n-4) = 0, n >= 4, a(0)=0, a(1)=a(2)=1, a(3)=2^3. See 5th row of signed Fibonomial triangle for coefficients: A055870(4, m), m=0..4
a(n) = (Fibonacci(3n) - 3(-1)^n*Fibonacci(n))/5. - Ralf Stephan, May 14 2004
a(n) and a(n+1) are found as rightmost and leftmost terms (respectively) in M^n * [1 0 0 0] where M = the 4 X 4 upper triangular Pascal's triangle matrix [1 3 3 1 / 1 2 1 0 / 1 1 0 0 / 1 0 0 0]. E.g., Ma(4) = 27, a(5) = 125. M^4 * [1 0 0 0] = [125 75 45 27]; where 75 = A066259(4) and 45 = A066258(3). The characteristic polynomial of M = x^4 - 3x^3 - 6x^2 + 3x + 1. a(n)/a(n-1) of the sequence and companions tend to 2+sqrt(5) = 4.2360679..., an eigenvalue of M and a root of the polynomial. - Gary W. Adamson, Oct 31 2004
From R. J. Mathar, Oct 16 2006: (Start)
Sum_{j=0..n} binomial(n,j)*a(j) = (2^n*A001906(n) + 3*A000045(n))/5.
Sum_{j=0..n} (-1)^j*binomial(n,j)*a(j) = ((-2)^n*A000045(n) - 3*A001906(n))/5. (End)
G.f.: x*(1-2*x-x^2)/((1+x-x^2)*(1-4*x-x^2)). - Colin Barker, Feb 28 2012
a(n) = F(n-2)*F(n+1)^2 + F(n-1)*(-1)^n. - J. M. Bergot, Mar 17 2016
a(n) = ((-3*(1/2*(-1-sqrt(5)))^n-(2-sqrt(5))^n+3*(1/2*(-1+sqrt(5)))^n+(2+sqrt(5))^n)) / (5*sqrt(5)). - Colin Barker, Jun 04 2016
a(n) = F(n-1)*F(n)*F(n+1) + F(n)*(-1)^(n-1). - Tony Foster III, Apr 11 2018
5*a(n) = L(2*n-1)*F(n+2) - L(2*n+1)*F(n-2) - 7*(-1)^n*F(n), where L(n) = A000032(n). - Peter Bala, Nov 12 2019
F(n+1)*F(n)*F(n-1) = 2*Sum_{j=1..n-1} P(j)*a(n-j) for n>0, where Pell number P(n) = A000129(n). - Michael A. Allen, Jan 11 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].

A379048 Irregular triangular array: row n is the linear recurrence signature of F(i)^n - F(i-1)^n, where F = A000045 (Fibonacci numbers).

Original entry on oeis.org

1, 1, 2, 2, -1, 3, 6, -3, -1, 4, 19, 4, -1, 8, 40, -60, -40, 8, 1, 13, 104, -260, -260, 104, 13, -1, 21, 273, -1092, -1820, 1092, 273, -21, -1, 33, 747, -3894, -16270, -3894, 747, 33, -1, 55, 1870, -19635, -85085, 136136, 85085, -19635, -1870, 55, 1, 89
Offset: 1

Views

Author

Clark Kimberling, Dec 16 2024

Keywords

Comments

(column 1) = (1, 2, 3, 4, 8, 13, 21, 33, 55, 89, 144, 232, ...) is linearly recurrent with signature (1,1,0,1,-1,-1).
(column 2) = (1, 2, 6, 19, 40, 104, 273, 747, 1870, 4895, 12816, 33784, ...) is linearly recurrent with signature (3, -1, 0, 8, -24, 8, 0, -8, 24, -8, 0, 1, -3, 1).
Row n is also the linear recurrence signature of L(i)^n - L(i-1)^n, where L = A000032 (Lucas numbers).

Crossrefs

Programs

  • Mathematica
    z = 25; w[i_] := Fibonacci[i];
    t[p_] := Table[w[i]^p - w[i - 1]^p, {i, 1, z}];
    Column[Table[FindLinearRecurrence[t[p]], {p, 1, 12}]]  (* array *)
    Flatten[Table[FindLinearRecurrence[t[p]], {p, 1, 12}]]    (* sequence *)

Formula

First 10 rows:
1 1
2 2 -1
3 6 -3 -1
4 19 4 -1
8 40 -60 -40 8 1
13 104 -260 -260 104 13 -1
21 273 -1092 -1820 1092 273 -21 -1
33 747 -3894 -16270 -3894 747 33 -1
55 1870 -19635 -85085 136136 85085 -19635 -1870 55 1
89 4895 -83215 -582505 1514513 1514513 -582505 -83215 4895 89 -1
Showing 1-3 of 3 results.