OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
Binomial transform of (1, 4, 5, 0, 0, 0, ...).
a(n) = a(n-1) + 5*n - 6 (with a(1)=1). - Vincenzo Librandi, Nov 23 2010
a(n) = (5*n^2 - 7*n + 4)/2. - Charles R Greathouse IV, Jun 17 2017
From Elmo R. Oliveira, Feb 08 2025: (Start)
G.f.: x*(2*x^2 + 2*x + 1)/(1-x)^3.
E.g.f.: exp(x)*(5*x^2 - 2*x + 4)/2 - 2.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n >= 4. (End)
PROG
(PARI) a(n)=(5*n^2-7*n+4)/2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Oct 14 2007
EXTENSIONS
a(47) onwards from Andrew Howroyd, Feb 08 2025
STATUS
approved