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Search: id:A129207
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| A129207 |
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Second sequence in solution to congruent number 5 problem. |
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+0
4
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| 1, 1, -49, -4799, 4728001, 18618840001, -767067390499249, -54213419267800732799, 250137278774864229623059201, -1127677799839642474480271473583999, -195577262542844878506138849501555847171249
(list; graph; listen)
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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.
X(2*n)= X(n)^4 -50* W(n)^4.
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)= n=abs(n); if(n<1, 1, if(n<4, [1, -49, -4799][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: A014773 A132539 A109344 this_sequence A053772 A075416 A127861
Adjacent sequences: A129204 A129205 A129206 this_sequence A129208 A129209 A129210
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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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