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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A156855 a(n) = 2025*n^2 - n. 4
 2024, 8098, 18222, 32396, 50620, 72894, 99218, 129592, 164016, 202490, 245014, 291588, 342212, 396886, 455610, 518384, 585208, 656082, 731006, 809980, 893004, 980078, 1071202, 1166376, 1265600, 1368874, 1476198, 1587572, 1702996, 1822470 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The identity (32805000*n^2 - 16200*n+1)^2 - (2025*n^2 - n)*(729000*n - 180)^2 = 1 can be written as A157080(n)^2 - a(n)*A156867(n)^2 = 1. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..10000 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*(2024+2026*x)/(1-x)^3. E.g.f.: x*(2024 + 2025*x)*exp(x). - G. C. Greubel, Jan 28 2022 MATHEMATICA Table[n (2025*n - 1), {n, 40}] (* Wesley Ivan Hurt, Oct 10 2021 *) PROG (Magma) I:=[2024, 8098, 18222]; [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)=2025*n^2-n \\ Charles R Greathouse IV, Dec 23 2011 (Sage) [n*(2025*n -1) for n in (1..40)] # G. C. Greubel, Jan 28 2022 CROSSREFS Cf. A156856, A156867, A157080. Sequence in context: A359839 A126821 A333057 * A306870 A126172 A183999 Adjacent sequences: A156852 A156853 A156854 * A156856 A156857 A156858 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Feb 17 2009; corrected Feb 20 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 February 20 20:53 EST 2024. Contains 370217 sequences. (Running on oeis4.)