OFFSET
2,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 2..1000
Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
Index entries for linear recurrences with constant coefficients, signature (11,-11,11,-11,11,-10).
FORMULA
a(n) = 10^n-floor(10^n/6)-floor(10^n/35)+floor(10^n/210).
From Colin Barker, Nov 17 2015: (Start)
a(n) = 11*a(n-1)-11*a(n-2)+11*a(n-3)-11*a(n-4)+11*a(n-5)-10*a(n-6) for n>7.
G.f.: -x^2*(90*x^5-89*x^4+95*x^3-88*x^2+92*x-82) / ((x-1)*(10*x-1)*(x^2-x+1)*(x^2+x+1)).
(End)
MAPLE
f := n->10^n-floor(10^n/2)-floor(10^n/35)+floor(10^n/210);
PROG
(Magma) [10^n-Floor(10^n/6)-Floor(10^n/35)+Floor(10^n/210): n in [2..20]]; // Vincenzo Librandi, Oct 02 2011
(PARI) Vec(-x^2*(90*x^5-89*x^4+95*x^3-88*x^2+92*x-82)/((x-1)*(10*x-1)*(x^2-x+1)*(x^2+x+1)) + O(x^30)) \\ Colin Barker, Nov 17 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Milan Janjic, Apr 28 2007
STATUS
approved