A189741 - OEIS

%I #34 Feb 18 2024 03:35:24

%S 4,2,16,68,304,1352,6016,26768,119104,529952,2358016,10491968,

%T 46683904,207719552,924246016,4112423168,18298184704,81417585152,

%U 362266710016,1611902010368,7172141461504,31912369866752,141993762390016,631799789293568,2811186681954304

%N a(1)=4, a(2)=2, a(n) = 4*a(n-1) + 2*a(n-2).

%H Vincenzo Librandi, <a href="/A189741/b189741.txt">Table of n, a(n) for n = 1..100</a>

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,2).

%F G.f.: 2*x*(2-7*x)/(1-4*x-2*x^2). - _Bruno Berselli_, May 24 2011

%t LinearRecurrence[{4,2},{4,2},40]

%o (Maxima) a[1]:4$ a[2]:2$ a[n]:=4*a[n-1]+2*a[n-2]$ makelist(a[n], n, 1, 25);  /* _Bruno Berselli_, May 24 2011 */

%Y Cf. A000045, A000079, A105476, A159612, A080040, A135522, A103435, A189732, A189734, A189735, A189736, A189737, A189738, A189739, A189742, A189743, A189744, A189745, A189746, A189747, A189748, A189749.

%K nonn,easy

%O 1,1

%A _Harvey P. Dale_, Apr 26 2011