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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A285851 Denominator of the ratio of alternate consecutive prime gaps: Denominator((prime(n + 3) - prime(n + 2))/(prime(n + 1) - prime(n))).

Original entry on oeis.org

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

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Author

Andres Cicuttin, Apr 27 2017

Keywords

Crossrefs

Cf. A286634 (numerators), A001223, A000040, A274225, A276309.

Programs

  • Mathematica
    Table[Denominator[(Prime[k+3]-Prime[k+2])/(Prime[k+1]-Prime[k])],{k,100}]

Formula

a(n) = denominator((prime(n + 3) - prime(n + 2))/(prime(n + 1) - prime(n))).
A000040(n+3) = 5 + Sum_{k=1..n} ((1+(-1)^k)*Product_{j=1..k}(A286634(j)/a(j))^((1+(-1)^j)/2) + ((1-(-1)^k)/2)*Product_{j=1..k}(A286634(j)/a(j))^((1-(-1)^j)/2)), for n>0.
A001223(n+2) = (1+(-1)^n)*Product_{j=1..n}(A286634(j)/a(j))^((1+(-1)^j)/2) - ((-1+(-1)^n)/2)*Product_{j=1..n}(A286634(j)/a(j))^((1-(-1)^j)/2), for n>0.
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