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Search: id:A138721
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| A138721 |
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Concatenation of n digits 1, n digits 0 and n digits 1. |
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+0
15
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| 101, 110011, 111000111, 111100001111, 111110000011111, 111111000000111111, 111111100000001111111, 111111110000000011111111, 111111111000000000111111111, 111111111100000000001111111111
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) is also A145641(n) written in base 2. [From Omar E. Pol (info(AT)polprimos.com), Oct 15 2008]
a(n) has 3n digits. [From Omar E. Pol (info(AT)polprimos.com), Nov 12 2008]
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FORMULA
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a(n+1)=1000*[a(n)-(10^n-1)/9]+10^(2*n+2)+[10^(n+1)-1]/9, with a(0)=101 and n>=1. - Paolo P. Lava (ppl(AT)spl.at), Apr 16 2008
a(n)=-(1/9)+(10/9)*10^n-(100/9)*100^n+(1000/9)*1000^n, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Oct 09 2008]
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EXAMPLE
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Contribution from Omar E. Pol (info(AT)polprimos.com), Nov 12 2008: (Start)
n ....... Successive digits of a(n)
1 ............... ( 1 0 1 )
2 ............ ( 1 1 0 0 1 1 )
3 ......... ( 1 1 1 0 0 0 1 1 1 )
4 ...... ( 1 1 1 1 0 0 0 0 1 1 1 1 )
5 ... ( 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 )
(End)
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MAPLE
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P:=proc(n) local a, i; a:=101; print(a); for i from 1 by 1 to n do a:=(a-(10^i-1)/9)*1000+10^(2*i+2)+(10^(i+1)-1)/9; print(a); od; end: P(100); - Paolo P. Lava (ppl(AT)spl.at), Apr 16 2008
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CROSSREFS
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Cf. A145641. [From Omar E. Pol (info(AT)polprimos.com), Oct 15 2008]
Cf. A000533, A135577, A138120, A138144, A138145, A138146, A138826, A147757, A147759. [From Omar E. Pol (info(AT)polprimos.com), Nov 12 2008]
Sequence in context: A136098 A153807 A076127 this_sequence A015078 A031982 A015041
Adjacent sequences: A138718 A138719 A138720 this_sequence A138722 A138723 A138724
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KEYWORD
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base,easy,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Mar 29 2008
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