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A229278
Number of ascending runs in {1,...,4}^n.
2
0, 4, 26, 144, 736, 3584, 16896, 77824, 352256, 1572864, 6946816, 30408704, 132120576, 570425344, 2449473536, 10468982784, 44560285696, 188978561024, 798863917056, 3367254360064, 14156212207616, 59373627899904, 248489627877376, 1037938976620544
OFFSET
0,2
FORMULA
G.f.: -2*(3*x-2)*x/(4*x-1)^2.
a(n) = 2^(2*n-3)*(5*n+3) for n>0, a(0) = 0.
MAPLE
a:= n-> `if`(n=0, 0, 2^(2*n-3)*(5*n+3)):
seq(a(n), n=0..30);
CROSSREFS
Column k=4 of A229079.
Sequence in context: A316539 A197964 A100236 * A180226 A325587 A223627
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Sep 18 2013
STATUS
approved