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A138119
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Concatenation of n digits 1 and 2n-1 digits 0.
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7
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10, 11000, 11100000, 11110000000, 11111000000000, 11111100000000000, 11111110000000000000, 11111111000000000000000, 11111111100000000000000000, 11111111110000000000000000000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) has 3n-1 digits.
a(n) is also A147538(n) written in base 2. [From Omar E. Pol (info(AT)polprimos.com), Nov 08 2008]
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FORMULA
| a(n)=[(10^n-1)*10^(2n-1)]/9, with n>=1 [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 26 2008]
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EXAMPLE
| n ...... a(n)
1 ....... 10
2 ...... 11000
3 ..... 11100000
4 .... 11110000000
5 ... 11111000000000
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CROSSREFS
| Cf. A138118, A138145, A138146, A138147, A138719, A138720, A138721, A138722.
Cf. A147538. [From Omar E. Pol (info(AT)polprimos.com), Nov 08 2008]
Sequence in context: A101305 A001098 A086164 * A138118 A091253 A151582
Adjacent sequences: A138116 A138117 A138118 * A138120 A138121 A138122
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KEYWORD
| base,easy,nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Apr 03 2008
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