This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A157844 103680000n^2 - 161251200n + 62697601. 3
 5126401, 154915201, 512064001, 1076572801, 1848441601, 2827670401, 4014259201, 5408208001, 7009516801, 8818185601, 10834214401, 13057603201, 15488352001, 18126460801, 20971929601, 24024758401, 27284947201, 30752496001 (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 a(n)^2-A157842(n)*A157843(n)^2=1. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..10000 Vincenzo Librandi, X^2-AY^2=1 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). G.f.: x*(-5126401-139535998*x-62697601*x^2)/(x-1)^3. MATHEMATICA LinearRecurrence[{3, -3, 1}, {5126401, 154915201, 512064001}, 40] PROG (MAGMA) I:=[5126401, 154915201, 512064001]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]]; (PARI) a(n) = 103680000*n^2 - 161251200*n + 62697601. CROSSREFS Cf. A157842, A157843. Sequence in context: A234785 A206136 A186624 * A263039 A241607 A140658 Adjacent sequences:  A157841 A157842 A157843 * A157845 A157846 A157847 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Mar 07 2009 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 10 12:30 EST 2019. Contains 329895 sequences. (Running on oeis4.)