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.

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A088545 Quotient Fibonacci(5*n)/(5*Fibonacci(n)), where Fibonacci(n) = A000045(n).

Original entry on oeis.org

1, 11, 61, 451, 3001, 20801, 141961, 974611, 6675901, 45768251, 313671601, 2150012161, 14736206161, 101003973851, 692290189501, 4745031073651, 32522917584361, 222915417520961, 1527884938291801, 10472279325329251, 71778069881360701, 491974211042344811, 3372041404278257761
Offset: 1

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Author

Lekraj Beedassy, Nov 17 2003

Keywords

Comments

The sequences {Fibonacci(k*n)/(Fibonacci(k)*Fibonacci(n)): n >= 1} are integral in the three cases k = 1 (A000012), k = 2 (A000032) and k = 5 (the present sequence). See Young, Section 4. - Peter Bala, Jan 09 2023

Crossrefs

Programs

  • PARI
    a(n)=fibonacci(5*n)/(5*fibonacci(n)); \\ Joerg Arndt, Jul 16 2013

Formula

a(n) = 5*Fib(n)^2*(Fib(n)^2 + (-1)^n) + 1 = 5*A007598(n)*A059929(n+1) + 1.
a(n) = A103326(n) / 5.
G.f.: -x*(x^4-4*x^3-9*x^2+6*x+1) / ((x-1)*(x^2-7*x+1)*(x^2+3*x+1)). - Colin Barker, Jul 16 2013
The expansion of exp(Sum_{n >= 1} a(n)*x^n/n) = 1 + x + 6*x^2 + 26*x^3 + 151*x^4 + 851*x^5 + 5101*x^6 + ... has integral coefficients and is equal to G(x)^(1/5), where G(x) is the o.g.f. of A001656. See Young, Theorem 3. - Peter Bala, Jan 09 2023
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