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%I #26 Oct 12 2017 10:04:54
%S 8,17,41,113,353,1217,4481,17153,67073,265217,1054721,4206593,
%T 16801793,67158017,268533761,1073938433,4295360513,17180655617,
%U 68721049601,274881052673,1099517919233,4398059094017,17592211210241,70368794509313,281475077373953,1125900108169217,4503600030023681,18014399314788353,72057595648540673
%N a(n) = (2^n+3)^2-8.
%H Daniel Shanks, <a href="https://doi.org/10.1090/S0025-5718-1971-0297737-4">Gauss's ternary form reduction and the 2-Sylow subgroup</a>, Math. Comp. 25 (1971), 837-853.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (7,-14,8).
%F a(n) = 7*a(n-1)-14*a(n-2)+8*a(n-3). G.f.: -(34*x^2-39*x+8)/((x-1)*(2*x-1)*(4*x-1)). [_Colin Barker_, Nov 11 2012]
%t (2^Range[0,30]+3)^2-8 (* or *) LinearRecurrence[{7,-14,8},{8,17,41},30] (* _Harvey P. Dale_, Nov 23 2012 *)
%Y For primes see A188661 and A188936.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_, Apr 14 2011
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