1,1

If A=[A157842] 3600*n.^2-5599*n +2177 (178, 5379, 17780,.,); Y=[A157843] 1728000*n - 1343760 (384240, 2112240..,); X=[A157844] 103680000*n^2-161251200*n +62697601 (5126401, 154915201,.,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 5126401^2-178 *384240^2=1; 154915201^2-5379*2112240^2=1.

Vincenzo Librandi, X^2-AY^2=1

Edward Everett Withford, Pell Equation

Wolfram MathWorld, Pell Equation

a(n)=103680000*n^2-161251200*n+62697601 (n>0)

For n=1, a(1)=5126401; n=2, a(2)=154915201

Cf. A157842, A157843

Sequence in context: A106785 A034607 A015363 this_sequence A140658 A125780 A116105

Adjacent sequences: A157841 A157842 A157843 this_sequence A157845 A157846 A157847

nonn

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 07 2009