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.

A022121 Fibonacci sequence beginning 3, 8.

Original entry on oeis.org

3, 8, 11, 19, 30, 49, 79, 128, 207, 335, 542, 877, 1419, 2296, 3715, 6011, 9726, 15737, 25463, 41200, 66663, 107863, 174526, 282389, 456915, 739304, 1196219, 1935523, 3131742, 5067265, 8199007, 13266272, 21465279, 34731551, 56196830, 90928381, 147125211
Offset: 0

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From Wajdi Maaloul, Jun 20 2022: (Start)
a(n) is the number of ways to tile the figure below with squares and dominoes (a strip of length n+2 that contains two vertical strip of height 2 in its first and third tiles).
|||_|___ _
|||_|||_|...|_|
(End)

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Programs

Formula

G.f.: (3+5*x)/(1-x-x^2). - Philippe Deléham, Nov 19 2008
a(n) = F(n+2) + 2*L(n+1), where F(n) and L(n) are the n-th Fibonacci and Lucas number, respectively. - Rigoberto Florez, Jan 29 2020
E.g.f.: exp(-2*x/(1+sqrt(5)))*(-2*(5+6*sqrt(5))+(55+27*sqrt(5))*exp(sqrt(5)*x))/(5*(3+sqrt(5))). - Stefano Spezia, Jan 29 2020 after Rigoberto Florez
a(n) = Lucas(n+3) + Fibonacci(n-2). - Greg Dresden and Steve Warren, Feb 28 2022