A214067 a(n) = [(5/2)*[(5/2)*n]], where [ ] = floor.

0, 5, 12, 17, 25, 30, 37, 42, 50, 55, 62, 67, 75, 80, 87, 92, 100, 105, 112, 117, 125, 130, 137, 142, 150, 155, 162, 167, 175, 180, 187, 192, 200, 205, 212, 217, 225, 230, 237, 242, 250, 255, 262, 267, 275, 280, 287, 292, 300

Offset: 0

Author

Clark Kimberling, Jul 20 2012

Keywords

• nonn
• easy

Comments

Also, numbers congruent to {0,5,12,17} mod 25.

Links

• Clark Kimberling, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

Crossrefs

Cf. A214066, A214068.

Programs

Mathematica

f[n_]:=Floor[(5/2)Floor[5n/2]];
t=Table[f[n],{n,0,70}]

Formula

a(n) = (50*n - 7 + 5*(-1)^n + (1 + i)*(-i)^n + (1 - i)*i^n)/8, where i = sqrt(-1).

a(n) = a(n-1) + a(n-4) - a(n-5).

G.f.: f(x)/g(x), where f(x) = 5*x + 7*x^2 + 5*x^3 + 8*x^4 and g(x) = (1 + x + x^2 + x^3)*(1 - x)^2