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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A144809 Decimal expansion of the constant 3.39277252592669675143137... arising in A144785.

Original entry on oeis.org

3, 3, 9, 2, 7, 7, 2, 5, 2, 5, 9, 2, 6, 6, 9, 6, 7, 5, 1, 4, 3, 1, 3, 7, 0, 6, 5, 0, 1, 8, 1, 8, 7, 3, 7, 6, 8, 4, 7, 2, 0, 6, 6, 1, 5, 3, 0, 8, 5, 9, 8, 7, 8, 4, 6, 5, 4, 6, 0, 3, 6, 9, 2, 3, 1, 2, 1, 7, 2, 4, 7, 5, 9, 2, 4, 5, 9, 9, 0, 2, 6, 8, 3, 7, 9, 4, 0, 7, 5, 8, 0, 1, 3, 7, 5, 9, 3, 2, 4, 8, 8, 1, 4, 5, 5
Offset: 1

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Author

Artur Jasinski, Sep 21 2008

Keywords

Crossrefs

A129871 A variant of Sylvester's sequence: a(0)=1 and for n>0, a(n) = (a(0)*a(1)*...*a(n-1)) + 1.

Original entry on oeis.org

1, 2, 3, 7, 43, 1807, 3263443, 10650056950807, 113423713055421844361000443, 12864938683278671740537145998360961546653259485195807
Offset: 0

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Author

Ben Branman, Sep 16 2011

Keywords

Comments

A variant of A000058, starting with an extra 1.

References

  • Jean-Marie Monier, Analyse, Exercices corrigés, 2ème année, MP, Dunod, 1997, Exercice 3.3.4 page 284.

Crossrefs

Cf. A000058 which is the main entry for this sequence.
Cf. A118227.

Programs

  • Haskell
    a129871 n = a129871_list !! n
    a129871_list = 1 : a000058_list  -- Reinhard Zumkeller, Dec 18 2013
  • Mathematica
    a[0] = 1; a[n_] := a[n] = Product[a[k], {k, 0, n - 1}] + 1

Formula

For n>0, a(n) = A000058(n-1).
a(1) = 2, a(n+1) = a(n)^2 - a(n) + 1. a(n) = round(c^(2^n)), where c = 1.264... is the Vardi constant, A076393. - Thomas Ordowski, Jun 11 2013
From Bernard Schott, Apr 06 2021: (Start)
Sum_{n>=0} 1/a(n) = 2.
Sum_{n>=0} (-1)^(n+1)/a(n) = 2 * (A118227 - 1). (End)

Extensions

Corrected and rewritten by Ben Branman, Sep 16 2011
Edited by Max Alekseyev, Oct 11 2012

A077125 Decimal expansion of the constant c such that A007018(n)=floor(c^(2^n)).

Original entry on oeis.org

1, 5, 9, 7, 9, 1, 0, 2, 1, 8, 0, 3, 1, 8, 7, 3, 1, 7, 8, 3, 3, 8, 0, 7, 0, 1, 1, 8, 1, 5, 7, 4, 5, 5, 3, 1, 2, 3, 6, 2, 2, 2, 4, 9, 5, 3, 1, 8, 2, 1, 1, 4, 1, 9, 6, 5, 9, 1, 3, 9, 3, 0, 9, 4, 2, 2, 9, 6, 1, 6, 1, 9, 5, 6, 2, 2, 7, 9, 4, 9, 6, 8, 7, 6, 1, 1, 4, 7, 0, 6, 2, 8, 1, 9, 6, 3, 5, 1, 8, 2, 5, 0, 5, 6, 6
Offset: 1

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Author

Benoit Cloitre, Nov 29 2002

Keywords

Examples

			1.5979102180318731783380....
		

Crossrefs

Formula

Equals lim_{n -> oo} A007018(n)^(1/2^n).
Equals E^2 where E is the Vardi constant arising in the Sylvester sequence (A076393). - Gerald McGarvey, Dec 08 2007
Previous Showing 11-13 of 13 results.