OFFSET
0,2
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).
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
MATHEMATICA
f[n_]:=Floor[(5/2)Floor[5n/2]];
t=Table[f[n], {n, 0, 70}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 20 2012
STATUS
approved