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A189741
a(1)=4, a(2)=2, a(n) = 4*a(n-1) + 2*a(n-2).
14
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
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 */
KEYWORD
nonn,easy
AUTHOR
Harvey P. Dale, Apr 26 2011
STATUS
approved