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A157843 1728000n - 1343760. 3
384240, 2112240, 3840240, 5568240, 7296240, 9024240, 10752240, 12480240, 14208240, 15936240, 17664240, 19392240, 21120240, 22848240, 24576240, 26304240, 28032240, 29760240, 31488240, 33216240, 34944240, 36672240 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The identity (103680000*n^2-161251200*n+62697601)^2-(3600*n^2-5599*n+2177)*(1728000*n-1343760)^2=1 can be written as A157844(n)^2-A157842(n)*a(n)^2=1.
LINKS
Vincenzo Librandi, X^2-AY^2=1
FORMULA
a(n) = 2*a(n-1) -a(n-2).
G.f.: x*(384240+1343760*x)/(x-1)^2.
MATHEMATICA
LinearRecurrence[{2, -1}, {384240, 2112240}, 40]
PROG
(Magma) I:=[384240, 2112240]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
(PARI) a(n) = 1728000*n - 1343760.
CROSSREFS
Sequence in context: A271323 A205759 A205589 * A206167 A206381 A234216
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 07 2009
STATUS
approved

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Last modified July 23 21:46 EDT 2024. Contains 374575 sequences. (Running on oeis4.)