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A147816
Concatenation of n digits 1 and 2(n-1) digits 0.
4
1, 1100, 1110000, 1111000000, 1111100000000, 1111110000000000, 1111111000000000000, 1111111100000000000000, 1111111110000000000000000, 1111111111000000000000000000, 1111111111100000000000000000000, 1111111111110000000000000000000000
OFFSET
1,2
COMMENTS
a(n) is also A016152(n) written in base 2.
FORMULA
a(n) = A138119(n)/10.
a(n) = 1100*a(n-1)-100000*a(n-2). G.f.: x / ((100*x-1)*(1000*x-1)). - Colin Barker, Sep 16 2013
EXAMPLE
n ...... a(n)
1 ....... 1
2 ...... 1100
3 ..... 1110000
4 .... 1111000000
5 ... 1111100000000
MATHEMATICA
Array[(10^#-1)*10^(2*#-2)/9 &, 20] (* or *)
LinearRecurrence[{1100, -100000}, {1, 1100}, 20] (* Paolo Xausa, Feb 27 2024 *)
PROG
(PARI) Vec(x/((100*x-1)*(1000*x-1)) + O(x^100)) \\ Colin Barker, Sep 16 2013
KEYWORD
base,easy,nonn
AUTHOR
Omar E. Pol, Nov 13 2008
STATUS
approved