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A044973
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Numbers whose base-3 representation contains exactly one 0 and three 1's.
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1
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31, 37, 39, 95, 97, 103, 113, 115, 119, 123, 127, 129, 139, 145, 147, 175, 193, 199, 201, 287, 293, 295, 311, 313, 319, 341, 347, 349, 359, 371, 375, 383, 385, 389, 393, 397, 399, 419, 421, 427, 437, 439, 443, 447, 451, 453, 463
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OFFSET
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1,1
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LINKS
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EXAMPLE
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31 = 1011_3; 37 = 1101_3; 39 = 1110_3; 95 = 10112_3.
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MAPLE
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f:= proc(d) local x, R, i, j, j3;
x:= 3^d-1;
op(sort([seq(seq(x - add(3^j, j = j3) - 2*3^i, i= {$0..d-2} minus j3) , j3 =combinat:-choose({$0..d-1}, 3))]))
end proc:
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MATHEMATICA
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Select[Range[500], DigitCount[#, 3, 0]==1&&DigitCount[#, 3, 1]==3&] (* Harvey P. Dale, Jul 12 2019 *)
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PROG
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(PARI) isok(k) = my(d=digits(k, 3)); (#select(x->(x==0), d) == 1) && (#select(x->(x==1), d) == 3); \\ Michel Marcus, Apr 21 2021
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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