A178934 a(n) = floor((3*4^n + 2*3^n)/5).

1, 3, 13, 49, 186, 711, 2749, 10705, 41946, 165159, 652765, 2587441, 10278906, 40903047, 162974461, 649984657, 2594199066, 10359577575, 41386654237, 165391648753, 661101690426, 2643012047943, 10567864050493, 42258903778129

Offset

0,2

Links

Table of n, a(n) for n=0..23.

Formula

a(n) = 7*a(n-1) - 12*a(n-2) + a(n-4) - 7*a(n-5) + 12*a(n-6); initial terms are 1, 3, 13, 49, 186, 711.

a(n) = 6*a(n-1) - 6*a(n-2) - 6*a(n-3) - 5*a(n-4) - 12*a(n-5) - 6; initial terms are 1, 3, 13, 49, 186.

G.f.: (1-4*x+4*x^2-6*x^3-2*x^4+x^5)/((1-3*x)*(1-4*x)*(1-x^4)).

Prog

(Maxima) makelist(floor((3*4^n+2*3^n)/5), n, 0, 12);
(Magma) [ (3*4^n+2*3^n) div 5: n in [0..30] ]; // Vincenzo Librandi, Dec 31 2010
(PARI) a(n) = (3*4^n + 2*3^n)\5 \\ Michel Marcus, Apr 24 2018

Crossrefs

Cf. A178935, A178936.

Sequence in context: A048482 A094978 A251743 * A218420 A241775 A045908

Adjacent sequences: A178931 A178932 A178933 * A178935 A178936 A178937

Keyword

nonn,easy

Author

Emanuele Munarini, Dec 30 2010

Status

approved