A100924 -id:A100924 - cp's OEIS frontend

A100925 Continued fraction expansion of constant defined in A100924.

0, 1, 10, 1, 4, 6, 1, 7, 3, 1, 1, 5, 18, 7, 1, 3, 2, 133, 5, 1, 5, 4, 1, 4, 1, 11, 19, 1, 4, 4, 1, 7, 1, 23, 1, 4, 2, 4, 1, 13, 1, 1, 2, 17, 1, 4, 2, 1, 1, 5, 9, 3, 2, 207, 4, 1, 3, 4, 4, 31, 2, 28, 2, 2, 1, 1, 7, 3, 3, 3, 1, 1, 792, 9, 1, 7, 3, 2, 2, 5, 2, 4, 1, 1, 1, 64, 2, 1, 2, 4, 1, 4, 73, 2, 1, 1, 1

Offset: 0

Joseph Biberstine (jrbibers(AT)indiana.edu), Nov 22 2004

			0.9152947975135605797336153972856208111251020453695777508300794...

Cf. A100923, A100924 (decimal expansion).

ContinuedFraction[Sum[If[And[PrimeQ[6*k - 1], PrimeQ[6*k + 1]], 1, 0]*2^(-k), {k, 1, 500}], 110]

Offset changed by Andrew Howroyd, Aug 04 2024

A100923 a(n) = 1 iff 6n+1 and 6n-1 are both prime numbers (0 otherwise).

Original entry on oeis.org

1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0

Offset: 1

Joseph Biberstine (jrbibers(AT)indiana.edu), Nov 22 2004

nonn

Characteristic function of A002822. - Georg Fischer, Aug 04 2021

			a(3) = 1 because 6*3-1=17 and 6*3+1=19 are both prime.
a(4) = 0 because 6*4-1=23 is prime and 6*4+1=25 is not prime.
a(20) = 0 because 6*20-1=119 and 6*20+1=121 are both not prime.

Cf. A000040, A002822, A100924, A100925.

Table[If[And[PrimeQ[6*k - 1], PrimeQ[6*k + 1]], 1, 0], {k, 1, 110}]

cp's OEIS Frontend

A100925 Continued fraction expansion of constant defined in A100924.

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A100923 a(n) = 1 iff 6n+1 and 6n-1 are both prime numbers (0 otherwise).

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cp's OEIS Frontend

A100925 Continued fraction expansion of constant defined in A100924.

Views

Author

Keywords

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Crossrefs

Programs

Mathematica

Extensions

A100923 a(n) = 1 iff 6*n+1 and 6*n-1 are both prime numbers (0 otherwise).

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Author

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Examples

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Programs

Mathematica

A100923 a(n) = 1 iff 6n+1 and 6n-1 are both prime numbers (0 otherwise).