A189741 a(1)=4, a(2)=2, a(n) = 4*a(n-1) + 2*a(n-2).

4, 2, 16, 68, 304, 1352, 6016, 26768, 119104, 529952, 2358016, 10491968, 46683904, 207719552, 924246016, 4112423168, 18298184704, 81417585152, 362266710016, 1611902010368, 7172141461504, 31912369866752, 141993762390016, 631799789293568, 2811186681954304

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

Index entries for linear recurrences with constant coefficients, signature (4,2).

Formula

G.f.: 2*x*(2-7*x)/(1-4*x-2*x^2). - Bruno Berselli, May 24 2011

Mathematica

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

Prog

(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 */

Crossrefs

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

Sequence in context: A137393 A356569 A122749 * A303142 A328695 A285595

Adjacent sequences: A189738 A189739 A189740 * A189742 A189743 A189744

Keyword

nonn,easy

Author

Harvey P. Dale, Apr 26 2011

Status

approved