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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A302999 a(n) = Product_{k=1..n} (Fibonacci(k+2) - 1).

Original entry on oeis.org

1, 1, 2, 8, 56, 672, 13440, 443520, 23950080, 2107607040, 301387806720, 69921971159040, 26290661155799040, 16011012643881615360, 15786858466867272744960, 25195826113120167300956160, 65080818850189392138369761280, 272037822793791659138385602150400
Offset: 0

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Author

Ilya Gutkovskiy, Apr 17 2018

Keywords

Comments

a(n) = determinant of (n + 1) X (n + 1) matrix whose main diagonal consists of the consecutive Fibonacci numbers starting with Fibonacci(2) (1, 2, 3, 5, 8, 13, ...) and all other elements are 1's (see example).

Examples

			The matrix begins:
  1  1  1  1  1  1  1  1  ...
  1  2  1  1  1  1  1  1  ...
  1  1  3  1  1  1  1  1  ...
  1  1  1  5  1  1  1  1  ...
  1  1  1  1  8  1  1  1  ...
  1  1  1  1  1 13  1  1  ...
  1  1  1  1  1  1 21  1  ...
  1  1  1  1  1  1  1 34  ...
		

Crossrefs

Programs

  • Maple
    b:= proc(n) b(n):= `if`(n<1, [1$2][], (f->
          [f, b(n-1)[2]*(f-1)][])(b(n-1)+b(n-2)))
        end:
    a:= n-> b(n)[2]:
    seq(a(n), n=0..20);  # Alois P. Heinz, Apr 24 2018
  • Mathematica
    Table[Product[Fibonacci[k + 2] - 1, {k, 1, n}], {n, 0, 17}]
    Table[Product[Sum[Fibonacci[j], {j, 1, k}], {k, 1, n}], {n, 0, 17}]
    Table[Det[Table[If[i == j, Fibonacci[i + 1], 1], {i, 1, n + 1}, {j, 1, n + 1}]], {n, 0, 17}]

Formula

a(n) = Product_{k=1..n} A000071(k+2).
a(n) = Product_{k=1..n} Sum_{j=1..k} A000045(j).
a(n) ~ c * ((1 + sqrt(5))/2)^(n*(n+5)/2) / 5^(n/2), where c = 0.1972502311584232476952451740107000852343536766534965116633336539193... - Vaclav Kotesovec, Apr 17 2018
a(n) = A190535(n-3) for n > 3. - Alois P. Heinz, Apr 25 2018
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