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A044973 Numbers whose base-3 representation contains exactly one 0 and three 1's. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
31 = 1011_3; 37 = 1101_3; 39 = 1110_3; 95 = 10112_3.
MAPLE
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:
map(f, [$4..6]); # Robert Israel, Apr 20 2021
MATHEMATICA
Select[Range[500], DigitCount[#, 3, 0]==1&&DigitCount[#, 3, 1]==3&] (* Harvey P. Dale, Jul 12 2019 *)
PROG
(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
CROSSREFS
Cf. A007089 (numbers in base 3), A044971 (1 zero 1 one), A044972 (1 zero 2 ones), A044974 (1 zero 4 ones).
Sequence in context: A109293 A053684 A336178 * A230035 A051267 A073521
KEYWORD
nonn,base,look
AUTHOR
STATUS
approved

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Last modified April 16 01:01 EDT 2024. Contains 371696 sequences. (Running on oeis4.)