OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
a(n)=n*(2*n^2+5*n+9)/2 = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). G.f.: x*(8-5*x+3*x^2)/(x-1)^4. [From R. J. Mathar, May 31 2009]
a(n) = A162261(n) + 8*n. - L. Edson Jeffery, Oct 12 2012
MATHEMATICA
CoefficientList[Series[(8-5*x+3*x^2)/(x-1)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 30 2012 *)
PROG
(Magma) I:=[8, 27, 63, 122]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..50]]; // Vincenzo Librandi, Jun 30 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 31 2009
EXTENSIONS
Extended by R. J. Mathar, May 31 2009
STATUS
approved