%I
%S 1,3,7,13,15,19,25,27,31,37,39,43,49,51,55,61,63,67,73,75,79,85,87,91,
%T 97,99,103,109,111,115,121,123,127,133,135,139,145,147,151,157,159,
%U 163,169,171,175,181,183,187,193,195,199,205,207,211,217,219,223,229,231
%N Sequence remaining after third round of Flavius Josephus sieve; remove every fourth term of A047241.
%C Numbers {1, 3, 7} mod 12
%F From _Chai Wah Wu_, Jul 24 2016: (Start)
%F a(n) = a(n1) + a(n3)  a(n4) for n > 4.
%F G.f.: x*(5*x^3 + 4*x^2 + 2*x + 1)/(x^4  x^3  x + 1). (End)
%Y We have A000027 after 0 rounds of sieving, A005408 after 1 round of sieving, A047241 after 2 rounds, A056530 after 3 rounds, A056531 after 4 rounds, A000960 after all rounds. After n rounds the remaining sequence comprises A002944(n) numbers mod A003418(n+1), i.e. 1/(n+1) of them.
%K easy,nonn
%O 1,2
%A _Henry Bottomley_, Jun 19 2000
