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

%I

%S 1,3,33,55,555,777,7777,9999,99999,1111111111,111111111111,

%T 131313131313,13131313131313,15151515151515,1515151515151515,

%U 1717171717171717,171717171717171717,191919191919191919,19191919191919191919,21212121212121212121,2121212121212121212121

%N A008619(n-1)-fold concatenation of A109613(n).

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

%C 1,

%C 3,

%C 33,

%C 55,

%C 555,

%C 777,

%C ...

%p cat2 := proc(a,b) a*10^(max(1,1+ilog10(b)))+b ; end proc:

%p A008619 := proc(n) 1+floor(n/2) ; end proc:

%p A109613 := proc(n) 2*floor(n/2)+1 ; end proc:

%p 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:

%p seq(A180116(n),n=1..24) ; # _R. J. Mathar_, Sep 19 2010

%Y Cf. A000217, A109613, A008619.

%K nonn,base,less

%O 1,2

%A _Mark Dols_, Aug 10 2010

%E Edited by _R. J. Mathar_, Sep 19 2010

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Last modified September 18 09:22 EDT 2020. Contains 337166 sequences. (Running on oeis4.)