OFFSET
0,2
REFERENCES
L. Berzolari, Allgemeine Theorie der Höheren Ebenen Algebraischen Kurven, Encyclopädie der Mathematischen Wissenschaften mit Einschluss ihrer Anwendungen. Band III_2. Heft 3, Leipzig: B. G. Teubner, 1906. p. 341.
LINKS
Bruno Berselli, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 9*(n-2)*(3*n-8), with offset 2.
a(n) = A000567(n)*9. - Omar E. Pol, Dec 11 2008
a(n) = a(n-1) + 54*n - 45, with n>0, a(0)=0. - Vincenzo Librandi, Dec 15 2010
G.f.: 9*x*(1+5*x)/(1-x)^3. - Colin Barker, Feb 29 2012
MATHEMATICA
9*PolygonalNumber[8, Range[0, 40]] (* Requires Mathematica version 10 or later *) (* or *) LinearRecurrence[{3, -3, 1}, {0, 9, 72}, 40] (* Harvey P. Dale, Aug 01 2020 *)
PROG
(PARI) a(n)=9*n*(3*n-2) \\ Charles R Greathouse IV, Jun 16 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Antreas P. Hatzipolakis (xpolakis(AT)otenet.gr), Sep 22 2001
EXTENSIONS
Better definition, corrected offset and edited from Omar E. Pol, Dec 11 2008
STATUS
approved