This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A129208 Third sequence in solution to congruent number 5 problem. 4
 1, 2, 41, 1562, 3344161, -7118599318, 654686219104361, -128615821825334210638, 249850594047271558364480641, -1935878334514951131830244285524398, 160443526614433014168714029147613242401001 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Let W(n)=A129206(n), X(n)=A129207(n), Y(n)=A129208(n), Z(n)=A129209(n). LINKS FORMULA 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. Y(2*n) = Y(n)^4 + 25 * W(n)^4. a(n+2) * a(n-2) = -144*a(n+1) * a(n-1) + 2257 * a(n)^2. a(-n) = a(n). PROG (PARI) {a(n) = n=abs(n); if( n<1, 1, if( n<4, [2, 41, 1562][n], (-144 * a(n-1) * a(n-3) + 2257 * a(n-2)^2 ) / a(n-4) ))} CROSSREFS Sequence in context: A112767 A058246 A176941 * A133298 A054742 A113634 Adjacent sequences:  A129205 A129206 A129207 * A129209 A129210 A129211 KEYWORD sign AUTHOR Michael Somos, Apr 03 2007 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified May 26 04:23 EDT 2013. Contains 225653 sequences.