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Search: id:A087414
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| A087414 |
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Numbers n such that 2*n*k(n) is rational but not an integer, where k(n) is sum of successive remainders when computing the euclidean algorithm for (1,1/sqrt(n)) as defined in A086378 (MuPAD program is given there); numbers belonging to A086378 but not to A088900. |
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| 153, 1717, 2244, 2340, 3525, 3650, 6460, 7119, 7475, 10074, 14490, 19147, 20008, 20862, 21424, 21747, 24453, 25400, 26039, 27346, 28028, 28371, 31484, 35483, 37008, 44275, 44678, 45974, 50389, 52155, 62187, 63724, 64752
(list; graph; listen)
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OFFSET
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1,1
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PROGRAM
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(PARI) /* z(n)!=0 iff n is in the sequence */
z(n)= { local(a, b, c, d, e, f, g, h, i, j, k);
b=a=sqrtint(n); d=f=i=1; e=g=h=0; j=c=n-a^2; if(!c, return(0));
until((a==b)&&(c==j), k=d+a*e; f*=c; d=a*d+e*n; e=k; g+=i; i*=c;
k=g+a*h; g=a*g+h*n; h=k; k=(a+b)\c; g-=i*k; a=c*k-a; c=(n-a^2)/c);
d=d/f-1; e/=f; g/=i; h/=i; i=d^2-n*e^2; k=h*d-g*e; g=g*d-h*e*n;
b=n-a^2; a=b*g-c*a*i; c=b*k+i*c; b*=i; !a*(2%(b/gcd(b, n*c))); }
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CROSSREFS
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Cf. A086378 and A088900.
Adjacent sequences: A087411 A087412 A087413 this_sequence A087415 A087416 A087417
Sequence in context: A050209 A109142 A014576 this_sequence A073938 A111086 A049515
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KEYWORD
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nonn
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AUTHOR
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Thomas Baruchel (baruchel(AT)users.sourceforge.net), Oct 21 2003
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