OFFSET
0,1
COMMENTS
Also the sum of five consecutive triangular numbers starting with A000217(-3). - Bruno Berselli, Jun 18 2015
REFERENCES
Found on a quiz.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 5*n + a(n-1)-5 for n>0, a(0)=5. - Vincenzo Librandi, Aug 08 2010
a(0)=5, a(1)=5, a(2)=10; for n>2, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Mar 23 2013
G.f.: 5*(1-2*x+2*x^2)/(1-x)^3. - Wesley Ivan Hurt, May 02 2021
MATHEMATICA
Table[(5(n^2-n+2))/2, {n, 0, 50}] (* or *) LinearRecurrence[{3, -3, 1}, {5, 5, 10}, 50] (* Harvey P. Dale, Mar 23 2013 *)
PROG
(PARI) a(n)=5*(n^2-n+2)/2 \\ Charles R Greathouse IV, Jun 17 2017
(Magma) [5*(n^2-n+2)/2 : n in [0..80]]; // Wesley Ivan Hurt, May 02 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 25 2003
STATUS
approved