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

1,2

Comments

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

1,

3,

33,

55,

555,

777,

...

Links

Table of n, a(n) for n=1..21.

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

Cf. A000217, A109613, A008619.

Sequence in context: A084502 A248397 A069165 * A282039 A186680 A139222

Adjacent sequences: A180113 A180114 A180115 * A180117 A180118 A180119

Keyword

nonn,base,less

Author

Mark Dols, Aug 10 2010

Extensions

Edited by R. J. Mathar, Sep 19 2010

Status

approved