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A138118
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Concatenation of 2n-1 digits 1 and n digits 0.
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10
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10, 11100, 11111000, 11111110000, 11111111100000, 11111111111000000, 11111111111110000000, 11111111111111100000000, 11111111111111111000000000, 11111111111111111110000000000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) is also A147537(n) written in base 2. [From Omar E. Pol (info(AT)polprimos.com), Nov 08 2008]
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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 (mathar(AT)strw.leidenuniv.nl), Apr 03 2008
a(n)=-(10/9)*10^(n-1)+(100/9)*1000^(n-1), with n>=1 - Paolo P. Lava (paoloplava(AT)gmail.com), Jul 15 2008
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EXAMPLE
| n .......... a(n)
1 ........... 10
2 ......... 11100
3 ....... 11111000
4 ..... 11111110000
5 ... 11111111100000
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MATHEMATICA
| FromDigits/@Table[Join[PadRight[{}, 2n-1, 1], PadRight[{}, n, 0]], {n, 15}] (* From Harvey P. Dale, Dec 09 2011 *)
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CROSSREFS
| Cf. A138147, A138721.
Cf. A147537. [From Omar E. Pol (info(AT)polprimos.com), Nov 08 2008]
Sequence in context: A001098 A086164 A138119 * A091253 A151582 A190946
Adjacent sequences: A138115 A138116 A138117 * A138119 A138120 A138121
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KEYWORD
| easy,nonn,base
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Mar 29 2008
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