A101411 - OEIS

A101411

Denominator when the numerator of the continued fraction rational approximation of sqrt(2) is prime. Also the denominators of A086395(n).

2, 5, 12, 29, 169, 408, 470832, 6625109, 44560482149, 345869461223138161, 13558774610046711780701, 87275373599917999482560755526644279276078854297832438763690789

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..12.

PROG

(PARI) cfracnum(m, f) = { local(x, r, cfr, i, m1); default(realprecision, 3000); numer2=0; denom2=0; cfr = vector(m+100); x=f; for(n=0, m, i=floor(x); x=1/(x-i); cfr[n+1] = i; ); for(m1=0, m, r=cfr[m1+1]; forstep(n=m1, 1, -1, r = 1/r; r+=cfr[n]; ); numer=numerator(r); denom=denominator(r); if(ispseudoprime(numer), print1(denom", ")); ); default(realprecision, 28);

CROSSREFS

Cf. A086395.

Sequence in context: A324787 A333888 A228516 * A042789 A291253 A348619

Adjacent sequences: A101408 A101409 A101410 * A101412 A101413 A101414

KEYWORD

frac,nonn

AUTHOR

Cino Hilliard, Jan 15 2005

STATUS

approved