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A086383 Primes found among the denominators of the continued fraction rational approximations to sqrt(2). +0
5
2, 5, 29, 5741, 33461, 44560482149, 1746860020068409, 68480406462161287469, 13558774610046711780701, 4125636888562548868221559797461449, 4760981394323203445293052612223893281 (list; graph; listen)
OFFSET

1,1

MATHEMATICA

Select[Table[ChebyshevU[k, 3]-ChebyshevU[k-1, 3], {k, 0, 50}], PrimeQ] - Ed Pegg Jr (ed(AT)mathpuzzle.com), May 10 2007

PROGRAM

(PARI) \Continued fraction rational approximation of numeric constants f. m=steps. cfracdenomprime(m, f) = { default(realprecision, 3000); cf = vector(m+10); x=f; for(n=0, m, i=floor(x); x=1/(x-i); cf[n+1] = i; ); for(m1=0, m, r=cf[m1+1]; forstep(n=m1, 1, -1, r = 1/r; r+=cf[n]; ); numer=numerator(r); denom=denominator(r); if(ispseudoprime(denom), print1(denom, ", ")); ) }

CROSSREFS

Cf. A056869. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 12 2008]

Sequence in context: A000283 A121910 A073833 this_sequence A118612 A158866 A101078

Adjacent sequences: A086380 A086381 A086382 this_sequence A086384 A086385 A086386

KEYWORD

nonn

AUTHOR

Cino Hilliard (hillcino368(AT)gmail.com), Sep 06 2003; corrected Jul 30 2004

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Last modified December 15 00:47 EST 2009. Contains 170825 sequences.


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