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.

A140455 13-Fibonacci sequence.

Original entry on oeis.org

0, 1, 13, 170, 2223, 29069, 380120, 4970629, 64998297, 849948490, 11114328667, 145336221161, 1900485203760, 24851643870041, 324971855514293, 4249485765555850, 55568286807740343, 726637214266180309
Offset: 0

Views

Author

R. J. Mathar, Jul 22 2008

Keywords

Comments

The k-Fibonacci sequences for k=2..12 are A000129, A006190, A001076, A052918, A005668, A054413, A041025, A099371, A041041, A049666, A041061. This here is k=13. k=14 is A041085, k=16 A041113, k=18 A041145, k=20 A041181, k=22 A041221.
For more information about this type of recurrence follow the Khovanova link and see A054413, A086902 and A178765. - Johannes W. Meijer, Jun 12 2010
For n>=2, a(n) equals the permanent of the (n-1) X (n-1) tridiagonal matrix with 13's along the main diagonal and 1's along the superdiagonal and the subdiagonal. - John M. Campbell, Jul 08 2011
For n>=1, a(n) equals the number of words of length n-1 on alphabet {0,1,...,13} avoiding runs of zeros of odd length. - Milan Janjic, Jan 28 2015
From Michael A. Allen, Apr 21 2023: (Start)
Also called the 13-metallonacci sequence; the g.f. 1/(1-k*x-x^2) gives the k-metallonacci sequence.
a(n+1) is the number of tilings of an n-board (a board with dimensions n X 1) using unit squares and dominoes (with dimensions 2 X 1) if there are 13 kinds of squares available. (End)

Crossrefs

Row n=13 of A073133, A172236 and A352361 and column k=13 of A157103.

Programs

  • Maple
    F := proc(n,k) coeftayl( x/(1-k*x-x^2),x=0,n) ; end: for n from 0 to 20 do printf("%d,",F(n,13)) ; od:
  • Mathematica
    LinearRecurrence[{13, 1}, {0, 1}, 30] (* Vincenzo Librandi, Nov 17 2012 *)
  • Sage
    [lucas_number1(n,13,-1) for n in range(0, 18)] # Zerinvary Lajos, Apr 29 2009

Formula

O.g.f.: x/(1-13*x-x^2).
a(n) = 13*a(n-1) + a(n-2).
a(n-r)*a(n+r) - a(n)^2 = (-1)^(n+1-r)*a(r)^2.
a(n) = Sum_{i=0..floor((n-1)/2)} binomial(n,2i+1)*13^(n-1-2*i)*(13^2+4)^i/2^(n-1).
a(n) = ((13+sqrt(173))^n - (13-sqrt(173))^n)/(2^n*sqrt(173)). - Al Hakanson (hawkuu(AT)gmail.com), Jan 12 2009
From Johannes W. Meijer, Jun 12 2010: (Start)
a(2*n) = 13*A097844(n), a(2*n+1) = A098244(n).
a(3*n+1) = A041319(5*n), a(3*n+2) = A041319(5*n+3), a(3*n+3) = 2*A041319(5*n+4).
Limit_{k->oo} a(n+k)/a(k) = (A088316(n) + A140455(n)*sqrt(173))/2.
Limit_{n->oo} A088316(n)/A140455(n) = sqrt(173). (End)

A040110 Continued fraction for sqrt(122).

Original entry on oeis.org

11, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22
Offset: 0

Views

Author

Keywords

Examples

			11 + 1/(22 + 1/(22 + 1/(22 + 1/(22 + ...)))) = sqrt(122).
		

Crossrefs

Cf. A040000, A041220/A041221 (convergents).

Programs

  • Maple
    Digits := 100: convert(evalf(sqrt(N)),confrac,90,'cvgts'):
  • Mathematica
    ContinuedFraction[Sqrt[122],300] (* Vladimir Joseph Stephan Orlovsky, Mar 12 2011*)

Formula

From Elmo R. Oliveira, Feb 11 2024: (Start)
a(n) = 22 = A010861(n) for n >= 1.
G.f.: 11*(1+x)/(1-x).
E.g.f.: 22*exp(x) - 11.
a(n) = 11*A040000(n). (End)

A041220 Numerators of continued fraction convergents to sqrt(122).

Original entry on oeis.org

11, 243, 5357, 118097, 2603491, 57394899, 1265291269, 27893802817, 614928953243, 13556330774163, 298854205984829, 6588348862440401, 145242529179673651, 3201923990815260723, 70587570327115409557, 1556128471187354270977, 34305413936448909371051
Offset: 0

Views

Author

Keywords

Crossrefs

Cf. A041221.

Programs

  • Mathematica
    Numerator/@Convergents[Sqrt[122],20] (* Harvey P. Dale, Jun 04 2011 *)
    CoefficientList[Series[(11 + x)/(1 - 22 x - x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 31 2013 *)

Formula

From Philippe Deléham, Nov 21 2008: (Start)
a(n) = 22*a(n-1) + a(n-2) for n > 1, a(0)=11, a(1)=243.
G.f.: (11+x) / (1-22*x-x^2). (End)

Extensions

More terms from Colin Barker, Nov 05 2013
Showing 1-3 of 3 results.