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A097255
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Numbers whose set of base 9 digits is {0,8}.
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2
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0, 8, 72, 80, 648, 656, 720, 728, 5832, 5840, 5904, 5912, 6480, 6488, 6552, 6560, 52488, 52496, 52560, 52568, 53136, 53144, 53208, 53216, 58320, 58328, 58392, 58400, 58968, 58976, 59040, 59048, 472392, 472400, 472464, 472472, 473040
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OFFSET
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0,2
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COMMENTS
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n such that there exists a permutation p_1, ..., p_n of 1, ..., n such that i + p_i is a power of 9 for every i.
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LINKS
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FORMULA
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a(2n) = 9*a(n), a(2n+1) = a(2n)+8.
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MATHEMATICA
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fQ[n_]:=Union@Join[{0, 8}, IntegerDigits[n, 9]]=={0, 8}; Select[Range[0, 500000], fQ] (* or *) FromDigits[#, 9]&/@Tuples[{0, 8}, 6](* Vincenzo Librandi, May 25 2012 *)
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PROG
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(Magma) [n: n in [0..500000] | Set(IntegerToSequence(n, 9)) subset {0, 8}]; // Vincenzo Librandi, May 25 2012
(Maxima) a[0]:0$ a[n]:=9*a[floor(n/2)]+4*(1-(-1)^n)$ makelist(a[n], n, 0, 36); /* Bruno Berselli, May 26 2012 */
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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