A213035 a(n) = n^2 - floor(n/3)^2.

0, 1, 4, 8, 15, 24, 32, 45, 60, 72, 91, 112, 128, 153, 180, 200, 231, 264, 288, 325, 364, 392, 435, 480, 512, 561, 612, 648, 703, 760, 800, 861, 924, 968, 1035, 1104, 1152, 1225, 1300, 1352, 1431, 1512, 1568, 1653, 1740, 1800, 1891, 1984, 2048

Offset

0,3

Links

Table of n, a(n) for n=0..48.

Index entries for linear recurrences with constant coefficients, signature (1,0,2,-2,0,-1,1).

Formula

a(n) = a(n-1)+2*a(n-3)-2*a(n-4)-a(n-6)+a(n-7).

G.f.: (x + 3 x^2 + 4 x^3 + 5 x^4 + 3 x^5)/(((1 - x)^3)*(1 + x + x^2)^2)

Mathematica

a[n_] := n^2 - Floor[n/3]^2
Table[a[n], {n, 0, 90}]    (* A213035 *)

Crossrefs

Sequence in context: A267682 A194804 A169953 * A014146 A049845 A011896

Adjacent sequences: A213032 A213033 A213034 * A213036 A213037 A213038

Keyword

nonn,easy

Author

Clark Kimberling, Jun 06 2012

Status

approved