OFFSET
0,1
COMMENTS
These numbers are all composite. They are divisible by 3,7 or 11.
All terms are divisible by 11. - Jason Yuen, Sep 02 2024
LINKS
FORMULA
a(n) = 9*10^(n+1) + 9 + 70*(10^n-1)/9.
a(n) = 11*(80*10^n + 1)/9. - Jason Yuen, Sep 02 2024
From Alois P. Heinz, Sep 02 2024: (Start)
a(n) = 11*A059482(n+1).
G.f.: 11*(9-10*x)/((10*x-1)*(x-1)). (End)
PROG
(PARI) g(n, r=7, m=9) = /* Repeat rrr.. surrounded by 2 m's */ { for(x=0, n, y=m*10^(x+1)+m+r*10*(10^x-1)/9; print1(y", ") ) }
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Jul 16 2005
EXTENSIONS
Minor edits by N. J. A. Sloane, Aug 01 2010
a(0) prepended by Alois P. Heinz, Sep 02 2024
STATUS
approved