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URL: https://oeis.org/A255745

⇱ A255745 - OEIS


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A255745
a(1) = 1; for n > 1, a(n) = 11*10^{A000120(n-1)-1}.
5
1, 11, 11, 110, 11, 110, 110, 1100, 11, 110, 110, 1100, 110, 1100, 1100, 11000, 11, 110, 110, 1100, 110, 1100, 1100, 11000, 110, 1100, 1100, 11000, 1100, 11000, 11000, 110000, 11, 110, 110, 1100, 110, 1100, 1100, 11000, 110, 1100, 1100, 11000, 1100, 11000, 11000
OFFSET
1,2
COMMENTS
Also, this is a row of the square array A255740.
Partial sums give A255766.
Is this also A151787 written in base 2?
The answer to the above question is yes. - Paolo Xausa, Feb 18 2026
FORMULA
a(n) = A007088(A151787(n)). - Paolo Xausa, Feb 18 2026
EXAMPLE
Also, written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
1;
11;
11, 110;
11, 110, 110, 1100;
11, 110, 110, 1100, 110, 1100, 1100, 11000;
...
MATHEMATICA
Join[{1}, 11*10^(DigitSum[Range[100], 2] - 1)] (* Paolo Xausa, Feb 18 2026 *)
PROG
(PARI) a(n) = if (n==1, 1, 11*10^(hammingweight(n-1)-1)); \\ Michel Marcus, Mar 13 2015
KEYWORD
nonn
AUTHOR
Omar E. Pol, Mar 05 2015
EXTENSIONS
More terms from Michel Marcus, Mar 13 2015
STATUS
approved