A110532 a(n) = floor(n/2) + floor(n/5).

0, 0, 1, 1, 2, 3, 4, 4, 5, 5, 7, 7, 8, 8, 9, 10, 11, 11, 12, 12, 14, 14, 15, 15, 16, 17, 18, 18, 19, 19, 21, 21, 22, 22, 23, 24, 25, 25, 26, 26, 28, 28, 29, 29, 30, 31, 32, 32, 33, 33, 35, 35, 36, 36, 37, 38, 39, 39, 40, 40, 42, 42, 43, 43, 44, 45, 46, 46, 47, 47, 49, 49, 50, 50

Offset: 0

Author

Reinhard Zumkeller, Jul 25 2005

Keywords

• nonn
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 0..5000
• Index entries for linear recurrences with constant coefficients, signature (0,1,0,0,1,0,-1).

Crossrefs

Cf. A010761, A110533.

Programs

Mathematica

Table[Floor[n/2]+Floor[n/5],{n,0,80}] (* or *) LinearRecurrence[ {0,1,0,0,1,0,-1},{0,0,1,1,2,3,4},80] (* Harvey P. Dale, Dec 26 2015 *)

PARI

a(n)=n\2 + n\5 \\ Charles R Greathouse IV, Jun 11 2015

Formula

a(n) = A004526(n) + A002266(n).

G.f.: x^2*(1+x+x^2+2*x^3+2*x^4) / ( (1+x)*(x^4+x^3+x^2+x+1)*(x-1)^2 ). - R. J. Mathar, Feb 20 2011

a(n) = 7n/10 + O(1). - Charles R Greathouse IV, Jun 11 2015