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A131026
Periodic sequence (2, 2, 1, 0, 0, 1).
12
2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1
OFFSET
1,1
COMMENTS
Second column of triangular array T defined in A131022.
FORMULA
a(1) = a(2) = 2, a(3) = 1, a(4) = a(5) = 0, a(6) = 1; for n > 6, a(n) = a(n-6).
G.f.: (2-2*x+x^2)/((1-x)*(1-x+x^2)).
a(n) = A021823(n+2).
a(n) = floor(((n+3) mod 6)/4)+floor(((n+2) mod 3)/2). - Gary Detlefs, Oct 02 2013
a(n) = 1+2/sqrt(3)*sin(Pi/3*n). - Werner Schulte, Jul 21 2017
MATHEMATICA
PadRight[{}, 120, {2, 2, 1, 0, 0, 1}] (* or *) LinearRecurrence[{2, -2, 1}, {2, 2, 1}, 120] (* Harvey P. Dale, Jul 16 2012 *)
PROG
(PARI) {m=105; for(n=1, m, r=(n-1)%6; print1(if(r<2, 2, if(r==2||r==5, 1, 0)), ", "))}
(Magma) m:=105; [ [2, 2, 1, 0, 0, 1][(n-1) mod 6 + 1]: n in [1..m] ];
CROSSREFS
Cf. A131022, A021823. Other columns of T are in A088911, A131027, A131028, A131029, A131030.
Sequence in context: A198243 A164965 A021823 * A333839 A014604 A015199
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, following a suggestion of Paul Curtz, Jun 10 2007
STATUS
approved