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A118612

Denominator if the numerator and denominator of the continued fraction rational approximation of sqrt(2) are both prime.

2, 5, 29, 44560482149, 13558774610046711780701

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OFFSET

1,1

COMMENTS

Next term, if it exists, is bigger than 489 digits (the 1279th convergent to sqrt(2)).

LINKS

Table of n, a(n) for n=1..5.

Andrej Dujella, Mirela Jukić Bokun, Ivan Soldo, A Pellian equation with primes and applications to D(-1)-quadruples, arXiv:1706.01959 [math.NT], 2017.

MATHEMATICA

For[n = 2, n < 1500, n++, a := Join[{1}, Table[2, {i, 2, n}]]; If[PrimeQ[Denominator[FromContinuedFraction[a]]], If[PrimeQ[Numerator[FromContinuedFraction[a]]], Print[Denominator[FromContinuedFraction[a]]]]]] (* Stefan Steinerberger, May 09 2006 *)

CROSSREFS

A086397 has the numerators. This sequence is a subsequence of A000129, A086383 and A101411.

Sequence in context: A229918 A179554 A086383 * A187628 A158866 A101078

Adjacent sequences: A118609 A118610 A118611 * A118613 A118614 A118615

KEYWORD

frac,nonn

AUTHOR

Joshua Zucker, May 08 2006

STATUS

approved

URL: https://oeis.org/A118612

⇱ A118612 - OEIS