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A180116 A008619(n-1)-fold concatenation of A109613(n). 1
1, 3, 33, 55, 555, 777, 7777, 9999, 99999, 1111111111, 111111111111, 131313131313, 13131313131313, 15151515151515, 1515151515151515, 1717171717171717, 171717171717171717, 191919191919191919, 19191919191919191919, 21212121212121212121, 2121212121212121212121 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 7 22:44 EDT 2020. Contains 336279 sequences. (Running on oeis4.)