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Search: id:A129206
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| A129206 |
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First sequence in solution to congruent number 5 problem. |
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+0
4
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| 0, 1, -12, -2257, 1494696, 8914433905, -178761481355556, -62419747600438859233, -5354229862821602092291248, 1001926359199672697329083442936609, 50016678000996026579336936742637753055940
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OFFSET
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0,3
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COMMENT
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Let W(n)=A129206(n), X(n)=A129207(n), Y(n)=A129208(n), Z(n)=A129209(n).
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FORMULA
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Right triangle with sides |10*Y(n)*W(n)/ (X(n)*Z(n))|, |X(n)*Z(n)/ (Y(n)*W(n))|, |2*Y(2*n)/ W(2*n)| has area 5.
W(2*n)= (-1)^n* 2* W(n)* X(n)* Y(n)* Z(n).
a(n+2)* a(n-2)= 144* a(n+1)* a(n-1) +2257* a(n)^2. a(-n)= -a(n).
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PROGRAM
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(PARI) {a(n)= local(s=sign(n)); n=abs(n); if(n<1, 0, s*if(n<5, [1, -12, -2257, 1494696][n], (144* a(n-1)* a(n-3) +2257* a(n-2)^2 )/a(n-4) ))}
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CROSSREFS
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Sequence in context: A101812 A064074 A005249 this_sequence A135398 A010053 A092299
Adjacent sequences: A129203 A129204 A129205 this_sequence A129207 A129208 A129209
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KEYWORD
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sign
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AUTHOR
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Michael Somos, Apr 03 2007
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