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A081475
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Consider the mapping f(a/b) = (a + b)/(2ab). Taking a = 1 b = 2 to start with and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 1/2,3/2,5/12,17/,137/4080,... Sequence contains the numerators.
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1
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1, 3, 7, 31, 367, 21199, 15311887, 648309901711, 19853227652502777487, 25742087295488761786102488482959, 1022127038655087543344600484892552190865956757100687
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| An infinite coprime sequence defined by recursion.
Every term is relatively prime to all others. - Michael Somos Feb 01 2004
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PROG
| (PARI) a(n)=local(v); if(n<2, n>0, v=[1, 2]; for(k=2, n, v=[v[1]+v[2], 2*v[1]*v[2]]); v[1])
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CROSSREFS
| Cf. A001685, A003686, A064526. The denominators are A081476.
Sequence in context: A156895 A074047 A121810 * A123212 A070231 A167917
Adjacent sequences: A081472 A081473 A081474 * A081476 A081477 A081478
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 24 2003
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EXTENSIONS
| Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003
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