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A128847 Denominators of the continued fraction convergents of the decimal concatenation of the upper bounds of twin primes. 0
1, 1, 2, 7, 1304, 1311, 2615, 139906, 142521, 424948, 1417365, 1842313, 3259678, 50737483, 53997161, 320723288, 374720449, 2569045982, 100567513747, 3603437154114739, 3603537721628486, 54052965256913543, 273868364006196201 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..22.

FORMULA

The upper bounds of twin primes 5,7,13,19... are concatenated and then preceded by a decimal point to create the fraction N = .57131931... . This number is then evaluated with n=0,m=steps to iterate,x = N, a(0)=floor(N) using the loop: do a(n)=floor(x) x=1/(x-a(n)) n=n+1 loop until n=m

PROG

(PARI) cattwinsU(n) = { a="."; forprime(x=3, n, if(ispseudoprime(x+2), a=concat(a, Str(x+2)))); a=eval(a) } cfrac2(m, f) = { default(realprecision, 1000); cf = vector(m+10); cf = contfrac(f); for(m1=1, m-1, r=cf[m1+1]; forstep(n=m1, 1, -1, r = 1/r; r+=cf[n]; ); numer=numerator(r); denom=denominator(r); print1(denom", "); ) }

CROSSREFS

Sequence in context: A056165 A082891 A000653 * A123180 A138198 A320505

Adjacent sequences:  A128844 A128845 A128846 * A128848 A128849 A128850

KEYWORD

frac,nonn,base

AUTHOR

Cino Hilliard, Apr 16 2007

EXTENSIONS

Edited by Charles R Greathouse IV, Apr 25 2010

STATUS

approved

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Last modified July 4 22:15 EDT 2020. Contains 335449 sequences. (Running on oeis4.)