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Search: id:A128847
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| A128847 |
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Denominators of the continued fraction convergents of the decimal concatenation of the upper bounds of twin primes. |
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+0
1
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| 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; listen)
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OFFSET
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0,3
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FORMULA
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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
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PROGRAM
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(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", "); ) }
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CROSSREFS
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Sequence in context: A056165 A082891 A000653 this_sequence A123180 A138198 A106023
Adjacent sequences: A128844 A128845 A128846 this_sequence A128848 A128849 A128850
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KEYWORD
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frac,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)hotmail.com), Apr 16 2007
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