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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 Robert Israel, Table of n, a(n) for n = 1..10000 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 Adjacent sequences: A044970 A044971 A044972 * A044974 A044975 A044976 KEYWORD nonn,base,look AUTHOR Clark Kimberling STATUS approved

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