A035513 Wythoff array read by falling antidiagonals.
1, 2, 4, 3, 7, 6, 5, 11, 10, 9, 8, 18, 16, 15, 12, 13, 29, 26, 24, 20, 14, 21, 47, 42, 39, 32, 23, 17, 34, 76, 68, 63, 52, 37, 28, 19, 55, 123, 110, 102, 84, 60, 45, 31, 22, 89, 199, 178, 165, 136, 97, 73, 50, 36, 25, 144, 322, 288, 267, 220, 157, 118, 81, 58, 41, 27, 233, 521
Offset: 1
A022124 Fibonacci sequence beginning 3, 13.
3, 13, 16, 29, 45, 74, 119, 193, 312, 505, 817, 1322, 2139, 3461, 5600, 9061, 14661, 23722, 38383, 62105, 100488, 162593, 263081, 425674, 688755, 1114429, 1803184, 2917613, 4720797, 7638410, 12359207
Offset: 0
Comments
For n >= 5, 4*a(n) is the number of ways to tile, with squares and dominoes, a horizontal strip of length n+1 that begins and ends with two vertical strips of heights 3 and 2. As an example, 4*a(7) = 4*193 = 772 is the number of ways to tile this figure (of length 8) with squares and dominoes.
Links
- Harvey P. Dale, Table of n, a(n) for n = 0..1000
- Tanya Khovanova, Recursive Sequences
- Index entries for linear recurrences with constant coefficients, signature (1,1).
Programs
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Mathematica
LinearRecurrence[{1,1},{3,13},40] (* Harvey P. Dale, Jun 08 2016 *)
Formula
G.f.: (3+10x)/(1-x-x^2). - Philippe Deléham, Nov 19 2008
a(n) = 5*Lucas(n+1) - 2*Fibonacci(n+1). - Lechoslaw Ratajczak, Apr 04 2021
A022408 a(n) = a(n-1) + a(n-2) + 1, with a(0)=3, a(1)=9.
3, 9, 13, 23, 37, 61, 99, 161, 261, 423, 685, 1109, 1795, 2905, 4701, 7607, 12309, 19917, 32227, 52145, 84373, 136519, 220893, 357413, 578307, 935721, 1514029, 2449751, 3963781, 6413533, 10377315, 16790849, 27168165, 43959015, 71127181, 115086197, 186213379, 301299577, 487512957
Offset: 0
Keywords
Links
- G. C. Greubel, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (2,0,-1)
Crossrefs
Cf. A022382.
Programs
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Magma
I:=[3,9,13]; [n le 3 select I[n] else 2*Self(n-1) - Self(n-3): n in [1..40]]; // G. C. Greubel, Mar 01 2018
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Mathematica
CoefficientList[Series[(3+3*x-5*x^2)/((x-1)*(x^2+x-1)), {x, 0, 50}], x] (* or *) LinearRecurrence[{2,0,-1}, {3,9,13}, 50] (* G. C. Greubel, Mar 01 2018 *) nxt[{a_,b_}]:={b,a+b+1}; NestList[nxt,{3,9},40][[;;,1]] (* Harvey P. Dale, Sep 13 2024 *)
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PARI
x='x+O('x^40); Vec((3+3*x-5*x^2)/((x-1)*(x^2+x-1))) \\ G. C. Greubel, Mar 01 2018
Formula
From R. J. Mathar, Mar 11 2011: (Start)
a(n+1) - a(n) = A022382(n-1).
G.f.: ( 3+3*x-5*x^2 ) / ( (x-1)*(x^2+x-1) ). (End)
a(n) = 2*Lucas(n+1) + 2*Fibonacci(n+2) - 1. - Greg Dresden, Oct 10 2020
Extensions
Terms a(31) onward added by G. C. Greubel, Mar 01 2018
Comments
Examples
References
Links
Crossrefs
Programs
Maple
Mathematica
PARI
Python
Python
Formula
Extensions