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A138118
Concatenation of 2n-1 digits 1 and n digits 0.
10
10, 11100, 11111000, 11111110000, 11111111100000, 11111111111000000, 11111111111110000000, 11111111111111100000000, 11111111111111111000000000, 11111111111111111110000000000
OFFSET
1,1
COMMENTS
a(n) is also A147537(n) written in base 2. [From Omar E. Pol, Nov 08 2008]
FORMULA
O.g.f.: 10*(1+100x)/[(-1+1000x)*(-1+10x)]. a(n)=A100706(n)*10^n = 10*a(n-1)+11*1000^n. - R. J. Mathar, Apr 03 2008
EXAMPLE
n .......... a(n)
1 ........... 10
2 ......... 11100
3 ....... 11111000
4 ..... 11111110000
5 ... 11111111100000
MATHEMATICA
FromDigits/@Table[Join[PadRight[{}, 2n-1, 1], PadRight[{}, n, 0]], {n, 15}] (* Harvey P. Dale, Dec 09 2011 *)
CROSSREFS
Cf. A147537.
Sequence in context: A086164 A138119 A327233 * A267130 A267850 A267206
KEYWORD
easy,nonn,base
AUTHOR
Omar E. Pol, Mar 29 2008
STATUS
approved