A187333 a(n) = floor(n/5) + floor(2n/5) + floor(3n/5) + floor(4n/5).

0, 0, 2, 4, 6, 10, 10, 12, 14, 16, 20, 20, 22, 24, 26, 30, 30, 32, 34, 36, 40, 40, 42, 44, 46, 50, 50, 52, 54, 56, 60, 60, 62, 64, 66, 70, 70, 72, 74, 76, 80, 80, 82, 84, 86, 90, 90, 92, 94, 96, 100, 100, 102, 104, 106, 110, 110, 112, 114, 116, 120, 120, 122, 124, 126, 130, 130, 132, 134, 136, 140, 140, 142, 144, 146, 150

Offset: 0

Author

Clark Kimberling, Mar 08 2011

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A187326.

Programs

Mathematica

Table[Floor[n/5]+Floor[2n/5]+Floor[3n/5]+Floor[4n/5], {n,0,120}]
Table[Total[Floor/@((Range[4]n)/5)],{n,0,80}] (* or *) LinearRecurrence[ {1,0,0,0,1,-1},{0,0,2,4,6,10},80] (* Harvey P. Dale, Oct 19 2018 *)

Formula

a(n) = floor(n/5)+floor(2n/5)+floor(3n/5)+floor(4n/5).

G.f.: 2*x^2*(1+x+x^2+2*x^3) / ( (x^4+x^3+x^2+x+1)*(x-1)^2 ). - R. J. Mathar, Mar 08 2011