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A173521
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a(n) is the concatenation of n 1's, 0, n 1's and 0.
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1
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0, 1010, 110110, 11101110, 1111011110, 111110111110, 11111101111110, 1111111011111110, 111111110111111110, 11111111101111111110, 1111111111011111111110, 111111111110111111111110
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OFFSET
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0,2
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COMMENTS
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a(n) is also A170940(n+1) written in base 2.
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LINKS
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FORMULA
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G.f.: 10*x*(200*x-101) / ((x-1)*(10*x-1)*(100*x-1)). [Colin Barker, Sep 17 2013]
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EXAMPLE
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n ............... a(n)
0 ................ 0
1 ............... 1010
2 .............. 110110
3 ............. 11101110
4 ............ 1111011110
5 ........... 111110111110
6 .......... 11111101111110
7 ......... 1111111011111110
8 ........ 111111110111111110
9 ....... 11111111101111111110
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MATHEMATICA
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Table[FromDigits[Join[PadRight[{}, n, 1], {0}, PadRight[{}, n, 1], {0}]], {n, 0, 20}] (* Harvey P. Dale, Feb 25 2012 *)
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PROG
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(PARI) Vec(10*x*(200*x-101)/((x-1)*(10*x-1)*(100*x-1)) + O(x^100)) \\ Colin Barker, Sep 17 2013
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CROSSREFS
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KEYWORD
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base,easy,nonn,changed
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AUTHOR
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STATUS
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approved
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