%I #20 Sep 10 2021 15:28:36
%S 2,6,8,32,144,192,768,3456,4608,18432,82944,110592,442368,1990656,
%T 2654208,10616832,47775744,63700992,254803968,1146617856,1528823808,
%U 6115295232,27518828544,36691771392,146767085568,660451885056
%N Three people (P1, P2, P3) are in a circle and are saying Hello to each other. They start with P2 saying "Hello, Hello". Thereafter Pn says "Hello" for n times the total number of Hello's so far.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,24).
%F G.f.: 2*x*(1-x)*(1+4*x+8*x^2)/(1-24*x^3). [_Colin Barker_, Jun 07 2012]
%t LinearRecurrence[{0,0,24},{2,6,8,32},30] (* _Harvey P. Dale_, Sep 10 2021 *)
%o (PARI) mod 3(n)=if (i%3==0,3,i%3) s=2; for (i=3,30,print1(s*mod 3(i),","); s=s+s*mod 3(i))
%Y Cf. A076508.
%K nonn,easy
%O 1,1
%A _Jon Perry_, Oct 15 2002
%E a(16) corrected by _Colin Barker_, Jun 07 2012
%E Better definition and corrected value for a(24) from _Sean A. Irvine_, May 19 2019