OFFSET
0,4
COMMENTS
For n = 0, 1, 2, 4, 8, 49, 98, 676, 1352, 9409, 18818, 131044, 262088, 1825201, 3650402, ... a(n) is a square.
LINKS
Bruno Berselli, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,2,-2,0,-1,1).
FORMULA
G.f.: x^3*(3 + x + x^2 + x^3)/((1 - x)^3*(1 + x + x^2)^2).
Sum_{n>=3} (-1)^(n+1)/a(n) = 9/4 + Pi^2/36 - Pi/(2*sqrt(3)) - 2*log(2). - Amiram Eldar, Mar 30 2023
MATHEMATICA
Table[n Floor[n/3], {n, 0, 60}]
PROG
(Magma) [n*Floor(n/3): n in [0..60]];
(Sage) [n*floor(n/3) for n in (0..60)];
(PARI) a(n)=n\3*n \\ Charles R Greathouse IV, Oct 07 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Bruno Berselli, Jul 01 2014
STATUS
approved