OFFSET
1,6
COMMENTS
See A194508.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).
FORMULA
From Chai Wah Wu, Jan 21 2020: (Start)
a(n) = a(n-1) + a(n-5) - a(n-6) for n > 6.
G.f.: x*(x^4 - x^3 + x^2 - x + 1)/(x^6 - x^5 - x + 1). (End)
a(n) = n - 2*floor((2*n + 2)/5). - Ridouane Oudra, Dec 25 2020
a(n) = a(n-1) + (-1)^((n-1) mod 5) for n > 1. - Alexander Van Plantinga, Dec 14 2021
EXAMPLE
This table shows (x(n),y(n)) for 1 <= n <= 13:
n...... 1..2..3..4..5..6..7..8..9..10..11..12..13
x(n).. -1..1..0..2..1..0..2..1..3..2...1...3...2
y(n)... 1..0..1..0..1..2..1..2..1..2...3...2...3
MATHEMATICA
c = 2; d = 3;
x1 = {-1, 1, 0, 2, 1}; y1 = {1, 0, 1, 0, 1};
x[n_] := If[n <= c + d, x1[[n]], x[n - c - d] + 1]
y[n_] := If[n <= c + d, y1[[n]], y[n - c - d] + 1]
Table[x[n], {n, 1, 100}] (* A194508 *)
Table[y[n], {n, 1, 100}] (* A194509 *)
r[1, n_] := n; r[2, n_] := x[n]; r[3, n_] := y[n]
TableForm[Table[r[m, n], {m, 1, 3}, {n, 1, 30}]]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Aug 27 2011
STATUS
approved