The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A158775 a(n) = 1600*n^2 + 40. 2
 1640, 6440, 14440, 25640, 40040, 57640, 78440, 102440, 129640, 160040, 193640, 230440, 270440, 313640, 360040, 409640, 462440, 518440, 577640, 640040, 705640, 774440, 846440, 921640, 1000040, 1081640, 1166440, 1254440, 1345640, 1440040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The identity (80*n^2 + 1)^2 - (1600*n^2 + 40)*(2*n)^2 = 1 can be written as A158776(n)^2 - a(n)*A005843(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 G.f.: -40*x*(41 + 38*x + x^2)/(x-1)^3. - R. J. Mathar, Jul 26 2009 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - R. J. Mathar, Jul 26 2009 MATHEMATICA LinearRecurrence[{3, -3, 1}, {1640, 6440, 14440}, 50] (* Vincenzo Librandi, Feb 20 2012 *) 1600*Range[30]^2+ 40 (* Harvey P. Dale, Jun 02 2020 *) PROG (Magma) I:=[1640, 6440, 14440]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 20 2012 (PARI) for(n=1, 40, print1(1600*n^2 + 40", ")); \\ Vincenzo Librandi, Feb 20 2012 CROSSREFS Cf. A005843, A158776. Sequence in context: A298075 A239160 A206234 * A234986 A043464 A002434 Adjacent sequences: A158772 A158773 A158774 * A158776 A158777 A158778 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Mar 26 2009 EXTENSIONS Edited by R. J. Mathar, Jul 26 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 3 11:24 EST 2022. Contains 358517 sequences. (Running on oeis4.)