%I A104177
%S A104177 1,3,7,9,15,19,21,31,33,37,39,45,51,61,63,67,69,75,79,81,93,97,99,109,
%T A104177 111,121,123,127,129,135,139,141,151,157,165,169,171,181,183,189,195,
%U A104177 199,201,211,213,219,225,229,231,241,243,247,249,255,261,271,277,279
%N A104177 A variation on Flavius's sieve (A000960): Start with the natural numbers; 
               at the k-th sieving step, remove every f-th term of the sequence 
               remaining after the (k-1)-st sieving step, where f is the (k+2)-nd 
               Fibonacci number, f=F(k+2); iterate.
%C A104177 This sequence is approximately as dense as the lucky numbers or primes: 
               there are 195 of these numbers, 153 lucky numbers and 168 primes 
               less than 1000.
%e A104177 Start with
%e A104177 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ... (A000027)
%e A104177 First sieving step: Delete every 2nd term (2=F(1+2)), giving
%e A104177 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 ... (A005408)
%e A104177 2nd sieving step: Delete every 3rd term (3=F(2+2)), giving
%e A104177 1 3 7 9 13 15 19 21 25 27 31 ... (A056530)
%e A104177 3rd sieving step: Delete every 5th (5=F(3+2)) term, giving
%e A104177 1 3 7 9 15 19 21 25 31 ...
%e A104177 4th sieving step: Delete every 8th (8=F(4+2)) term, giving
%e A104177 1 3 7 9 15 19 21 31 ...
%e A104177 Continue forever and whatever remains is the sequence.
%Y A104177 Cf. A000960, A000959, A099204, A000045.
%Y A104177 Sequence in context: A026175 A026139 A119681 this_sequence A099204 A070993 
               A128539
%Y A104177 Adjacent sequences: A104174 A104175 A104176 this_sequence A104178 A104179 
               A104180
%K A104177 easy,nonn
%O A104177 1,2
%A A104177 Tyler D. Rick (tyler.rick(AT)does.not.want.spam.com), Mar 11 2005