OFFSET
1,2
COMMENTS
Written underneath, the first terms have increasing lengths filling a triangular shape:
1,
3,
33,
55,
555,
777,
...
MAPLE
cat2 := proc(a, b) a*10^(max(1, 1+ilog10(b)))+b ; end proc:
A008619 := proc(n) 1+floor(n/2) ; end proc:
A109613 := proc(n) 2*floor(n/2)+1 ; end proc:
A180116 := proc(n) a := A109613(n) ; for t from 2 to A008619(n-1) do a := cat2(a, A109613(n)) ; end do: a ; end proc:
seq(A180116(n), n=1..24) ; # R. J. Mathar, Sep 19 2010
CROSSREFS
KEYWORD
nonn,base,less
AUTHOR
Mark Dols, Aug 10 2010
EXTENSIONS
Edited by R. J. Mathar, Sep 19 2010
STATUS
approved