OFFSET
0,1
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Patrick De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X).
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
For n>0: a(n) = A176271(n+1,2). - Reinhard Zumkeller, Apr 13 2010
a(n) = 2*n + a(n-1) (with a(0)=3). - Vincenzo Librandi, Aug 05 2010
From Colin Barker, Dec 29 2014: (Start)
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
G.f.: (3*x^2 - 4*x + 3)/(1 - x)^3. (End)
Sum_{n>=0} 1/a(n) = Pi*tanh(Pi*sqrt(11)/2)/sqrt(11). - Amiram Eldar, Jan 17 2021
MAPLE
with (combinat):seq(fibonacci(3, n)+n+2, n=0..47); # Zerinvary Lajos, Jun 07 2008
MATHEMATICA
Table[n^2 + n + 3, {n, 0, 50}] (* Bruno Berselli, Sep 03 2018 *)
PROG
(PARI) Vec((3*x^2-4*x+3)/(1-x)^3 + O(x^100)) \\ Colin Barker, Dec 29 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Definition and offset corrected by Franklin T. Adams-Watters, Jul 06 2009
STATUS
approved