cp's OEIS Frontend

A171949 P-positions for game of Mark-4.

%I A171949 #25 Apr 16 2023 08:30:37
%S A171949 0,4,8,12,20,24,28,36,40,44,52,56,60,64,68,72,76,84,88,92,100,104,108,
%T A171949 116,120,124,128,132,136,140,148,152,156,164,168,172,180,184,188,192,
%U A171949 196,200,204,212,216,220,228,232,236,244,248,252,260,264,268,276
%N A171949 P-positions for game of Mark-4.
%H A171949 Aviezri S. Fraenkel, <a href="http://dx.doi.org/10.1016/j.disc.2011.03.032">The vile, dopey, evil and odious game players</a>, Discrete Math. 312 (1) (2012) 42-46.
%F A171949 a(n) = 4*A171948(n).
%F A171949 Conjecture: For n>=2, a(n) = A217319(n-1). - _Vladimir Shevelev_, Mar 18 2013
%p A171949 isA171948 := proc(n)
%p A171949     option remember;
%p A171949     if n <=3 then
%p A171949         true;
%p A171949     elif isA171949(n) then
%p A171949         false;
%p A171949     else
%p A171949         true ;
%p A171949     end if;
%p A171949 end proc:
%p A171949 isA171949 := proc(n)
%p A171949     option remember;
%p A171949     if n mod 4 <> 0 then
%p A171949         return false;
%p A171949     end if;
%p A171949     if isA171948(n/4) then
%p A171949         true;
%p A171949     else
%p A171949         false ;
%p A171949     end if;
%p A171949 end proc:
%p A171949 for n from 0 to 400 do
%p A171949     if isA171949(n) then
%p A171949         printf("%d,",n);
%p A171949     end if;
%p A171949 end do: # _R. J. Mathar_, Mar 28 2013
%t A171949 isA171948[n_] := isA171948[n] =
%t A171949    If[n <= 3, True, If[isA171949[n], False, True]];
%t A171949 isA171949[n_] := isA171949[n] =
%t A171949    If[Mod[n, 4] != 0, False, If[isA171948[n/4], True, False]];
%t A171949 Select[Range[0, 400], isA171949] (* _Jean-François Alcover_, Apr 16 2023, after _R. J. Mathar_ *)
%Y A171949 Complement of A171948.
%Y A171949 Cf. A217319.
%K A171949 nonn,easy
%O A171949 1,2
%A A171949 _N. J. A. Sloane_, Oct 29 2010