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 A154968 a(n)=4*a(n-1)+12*a(n-2), n>2 ; a(0)=1, a(1)=1, a(2)=7 . 1
 1, 1, 7, 40, 244, 1456, 8752, 52480, 314944, 1889536, 11337472, 68024320, 408146944, 2448879616, 14693281792, 88159682560, 528958111744, 3173748637696, 19042491891712, 114254951219200, 685529707577344 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA G.f.: (1-3*x-9*x^2)/(1-4*x-12*x^2). a(n+1)=Sum_{k, 0<=k<=n}A154929(n,k)*3^(n-k). a(n)=(1/8)*[9*6^(n-1)-(-2)^(n-1)]+(3/4)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava, Jan 20 2009] CROSSREFS Sequence in context: A026782 A099459 A051814 * A121582 A226223 A062727 Adjacent sequences:  A154965 A154966 A154967 * A154969 A154970 A154971 KEYWORD nonn AUTHOR Philippe DELEHAM, Jan 18 2009 STATUS approved

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