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Search: id:A138147
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| A138147 |
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Concatenation of n digits 1 and n digits 0. |
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+0
6
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| 10, 1100, 111000, 11110000, 1111100000, 111111000000, 11111110000000, 1111111100000000, 111111111000000000, 11111111110000000000, 1111111111100000000000, 111111111111000000000000
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also, a(n) = binary representation of A020522(n), for n>0 (See example).
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FORMULA
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a(n) = (10^(2n) - 10^n)/9 = A002275(n)*10^n. - Omar E. Pol (info(AT)polprimos.com), Apr 16 2008
a(n) = A109241(n-1)*10. [From Omar E. Pol (info(AT)polprimos.com), Nov 08 2008]
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EXAMPLE
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n ... A020522(n) ..... a(n)
1 ....... 2 ........... 10
2 ...... 12 .......... 1100
3 ...... 56 ......... 111000
4 ..... 240 ........ 11110000
5 ..... 992 ....... 1111100000
6 .... 4032 ...... 111111000000
7 ... 16256 ..... 11111110000000
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CROSSREFS
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Cf. A020522, A138144, A138145, A138720.
Cf. A002275.
Cf. A109241, A138118, A138119, A138120, A138146, A138721, A138826. [From Omar E. Pol (info(AT)polprimos.com), Nov 08 2008]
Sequence in context: A133383 A071672 A122230 this_sequence A036058 A001155 A001391
Adjacent sequences: A138144 A138145 A138146 this_sequence A138148 A138149 A138150
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KEYWORD
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easy,nonn,base
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Mar 29 2008
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