OFFSET
1,1
COMMENTS
Fourth column of triangular array T defined in A131022.
Continued fractions of (131 + sqrt(18530))/37 = 7.2195930... - R. J. Mathar, Mar 08 2012
LINKS
FORMULA
a(1) = a(6) = 7, a(2) = a(5) = 4, a(3) = a(4) = 1; for n > 6, a(n) = a(n-6).
G.f.: x*(7-10*x+7*x^2)/((1-x)*(1-x+x^2)).
a(n) = A084104(n+2).
a(n) = 4+2*sqrt(3)*cos(Pi/6*(2*n-1)). - Werner Schulte, Jul 21 2017
MATHEMATICA
PadRight[{}, 120, {7, 4, 1, 1, 4, 7}] (* Harvey P. Dale, Jul 15 2013 *)
PROG
(PARI) {m=105; for(n=1, m, r=(n-1)%6; print1(if(r==0||r==5, 7, if(r==1||r==4, 4, 1)), ", "))}
(Magma) m:=105; [ [7, 4, 1, 1, 4, 7][(n-1) mod 6 + 1]: n in [1..m] ];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, following a suggestion of Paul Curtz, Jun 10 2007
STATUS
approved