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 A023706 Numbers with a single 0 in their base 4 expansion. 2
 0, 4, 8, 12, 17, 18, 19, 20, 24, 28, 33, 34, 35, 36, 40, 44, 49, 50, 51, 52, 56, 60, 69, 70, 71, 73, 74, 75, 77, 78, 79, 81, 82, 83, 84, 88, 92, 97, 98, 99, 100, 104, 108, 113, 114, 115, 116, 120, 124, 133, 134, 135, 137, 138, 139, 141 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Each member of the sequence is either 4*a+b for a in the sequence and b in {1,2,3}, or 4*a for a in A023705. - Robert Israel, Oct 04 2018 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 MAPLE R23705:= {1, 2, 3}: R:= {}: A:= 0; for i from 1 to 4 do   R:= map(t ->4*t, R23705) union map(t -> (4*t+1, 4*t+2, 4*t+3), R);   R23705:= map(t -> (4*t+1, 4*t+2, 4*t+3), R23705);   A:= A, op(sort(convert(R, list))); od: A; # Robert Israel, Oct 04 2018 MATHEMATICA Select[ Range[ 0, 160 ], (Count[ IntegerDigits[ #, 4 ], 0 ]==1)& ] PROG (PARI) isok(n) = (n==0) || (#select(x->(x==0), digits(n, 4)) == 1); \\ Michel Marcus, Oct 04 2018 CROSSREFS Cf. A023705. Sequence in context: A194374 A061085 A007883 * A043333 A037352 A311395 Adjacent sequences:  A023703 A023704 A023705 * A023707 A023708 A023709 KEYWORD nonn,base,easy AUTHOR STATUS approved

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Last modified January 27 17:58 EST 2020. Contains 331296 sequences. (Running on oeis4.)