A180116 A008619(n-1)-fold concatenation of A109613(n).

1, 3, 33, 55, 555, 777, 7777, 9999, 99999, 1111111111, 111111111111, 131313131313, 13131313131313, 15151515151515, 1515151515151515, 1717171717171717, 171717171717171717, 191919191919191919, 19191919191919191919, 21212121212121212121, 2121212121212121212121

Offset: 1

Author

Mark Dols, Aug 10 2010

Keywords

• nonn
• base
• less

Comments

Written underneath, the first terms have increasing lengths filling a triangular shape:

1,

3,

33,

55,

555,

777,

...

Crossrefs

Cf. A000217, A109613, A008619.

Programs

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

Extensions

Edited by R. J. Mathar, Sep 19 2010