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A101931
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Number of primitive Pythagorean triples with hypotenuse < 10^n.
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12
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1, 16, 158, 1593, 15919, 159139, 1591579, 15915492, 159154994, 1591549475, 15915494180, 159154943063, 1591549430580, 15915494309496, 159154943089963, 1591549430916326, 15915494309190251, 159154943091887752, 1591549430918979115
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OFFSET
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1,2
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COMMENTS
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The ratio a(n)/10^n as n->inf is 1/(2*Pi) = 0.15915... (Lehmer). - Tito Piezas III, Aug 11 2006
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LINKS
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EXAMPLE
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a(1)=1 because there is one primitive solution (a,b,c) as (3,4,5) with c<10^1.
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PROG
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(PARI) a(n)=my(t, lim=10^n); for(m=2, sqrtint(lim-1), forstep(n=1+m%2, min(sqrtint(lim-m^2), m-1), 2, if(gcd(m, n)==1, t++))); t \\ Charles R Greathouse IV, Sep 13 2012
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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More terms from Jan Feitsma and Bart Dopheide (dopheide(AT)fmf.nl), Mar 10 2005
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STATUS
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approved
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