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A011734
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A binary m-sequence: expansion of reciprocal of x^21 + x^2 + 1 (mod 2, shifted by 20 initial 0's).
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0
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0
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OFFSET
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0,1
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COMMENTS
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Sequence is 2^21-1 = 2097151-periodic. - M. F. Hasler, Feb 17 2018
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REFERENCES
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S. W. Golomb, Shift-Register Sequences, Holden-Day, San Francisco, 1967.
H. D. Lueke, Korrelationssignale, Springer 1992, pp. 43-48.
F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1978, p. 408.
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LINKS
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FORMULA
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G.f. = x^20/(x^21 + x^2 + 1), over GF(2). - M. F. Hasler, Feb 17 2018
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MATHEMATICA
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Join[PadRight[{}, 20, 0], (Mod[#, 2]&/@CoefficientList[Series[1/(x^21+x^2+1), {x, 0, 60}], x])] (* Harvey P. Dale, Jun 01 2020 *)
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PROG
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(PARI) A=matrix(N=21, N, i, j, if(i>1, i==j+1, setsearch([2, N], j)>0))*Mod(1, 2); a(n)=lift((A^(n-#A+1))[1, 1]) \\ M. F. Hasler, Feb 17 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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