%I A135491
%S A135491 2,4,8,14,26,48,88,162,298,548,1008,1854,3410,6272,11536,21218,39026,
%T A135491 71780,132024,242830,446634,821488,1510952,2779074,5111514,9401540,
%U A135491 17292128,31805182,58498850,107596160,197900192,363995202,669491554
%N A135491 Number of ways to toss a coin n times and not get a run of four.
%F A135491 a(n)=a(n-1)+a(n-2)+a(n-3)
%t A135491 a[n_] := a[n] = a[n - 1] + a[n - 2] + a[n - 3]; a[1] = 2; a[2] = 4; a[3] 
               = 8; Array[a, 33] - Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 10 
               2008
%Y A135491 a(n)=2*A000073(n+2). Cf. A135492, A135493.
%Y A135491 Sequence in context: A130708 A054193 A117633 this_sequence A164154 A164156 
               A164155
%Y A135491 Adjacent sequences: A135488 A135489 A135490 this_sequence A135492 A135493 
               A135494
%K A135491 nonn
%O A135491 1,1
%A A135491 James R FitzSimons (cherry(AT)getnet.net), Feb 07 2008
%E A135491 More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 10 2008