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.

A157725 a(n) = Fibonacci(n) + 2.

Original entry on oeis.org

2, 3, 3, 4, 5, 7, 10, 15, 23, 36, 57, 91, 146, 235, 379, 612, 989, 1599, 2586, 4183, 6767, 10948, 17713, 28659, 46370, 75027, 121395, 196420, 317813, 514231, 832042, 1346271, 2178311, 3524580, 5702889, 9227467, 14930354, 24157819, 39088171, 63245988, 102334157
Offset: 0

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Author

N. J. A. Sloane, Jun 26 2010

Keywords

Comments

a(n) = A226649(2*n+1) - A226649(2*n). - Reinhard Zumkeller, Jul 30 2013

Crossrefs

Programs

  • Haskell
    a157725 = (+ 2) . a000045
    a157725_list = 2 : 3 : map (subtract 2)
                           (zipWith (+) a157725_list $ tail a157725_list)
    -- Reinhard Zumkeller, Jul 30 2013
  • Magma
    [ Fibonacci(n) + 2: n in [0..40] ]; // Vincenzo Librandi, Apr 24 2011
    
  • Mathematica
    Fibonacci[Range[0, 50]] + 2 (* or *)
    LinearRecurrence[{2, 0, -1}, {2, 3, 3}, 50] (* Paolo Xausa, Jul 28 2024 *)
  • PARI
    a(n)=fibonacci(n)+2 \\ Charles R Greathouse IV, Jul 02 2013
    

Formula

G.f.: -(1+x)*(3*x-2) / ( (x-1)*(x^2+x-1) ). - R. J. Mathar, Aug 08 2012
a(0) = 2, a(1) = 3, a(n) = a(n - 2) + a(n - 1) - 2. - Reinhard Zumkeller, Jul 30 2013
E.g.f.: 2*(exp(x) + exp(x/2)*sinh(sqrt(5)*x/2)/sqrt(5)). - Stefano Spezia, Apr 09 2025