This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A056530 #16 Oct 19 2022 10:31:07
%S A056530 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 A056530 97,99,103,109,111,115,121,123,127,133,135,139,145,147,151,157,159,
%U A056530 163,169,171,175,181,183,187,193,195,199,205,207,211,217,219,223,229,231
%N A056530 Sequence remaining after third round of Flavius Josephus sieve; remove every fourth term of A047241.
%C A056530 Numbers {1, 3, 7} mod 12: A017533, A017557, A017605 interleaved.
%H A056530 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1).
%H A056530 <a href="/index/J#Josephus">Index entries for sequences related to the Josephus Problem</a>
%F A056530 From _Chai Wah Wu_, Jul 24 2016: (Start)
%F A056530 a(n) = a(n-1) + a(n-3) - a(n-4) for n > 4.
%F A056530 G.f.: x*(5*x^3 + 4*x^2 + 2*x + 1)/(x^4 - x^3 - x + 1). (End)
%F A056530 a(n) = 4*n - (13 + 2*A131713(n))/3. - _R. J. Mathar_, Jun 22 2020
%t A056530 LinearRecurrence[{1,0,1,-1},{1,3,7,13},60] (* _Harvey P. Dale_, Oct 19 2022 *)
%Y A056530 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 A056530 easy,nonn
%O A056530 1,2
%A A056530 _Henry Bottomley_, Jun 19 2000