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A136427
a(n) = 3*a(n-1)-4*a(n-2)+6*a(n-3)-4*a(n-4).
0
0, 1, 2, 4, 10, 24, 48, 92, 188, 388, 772, 1524, 3060, 6164, 12308, 24532, 49108, 98388, 196692, 393044, 786260, 1573204, 3146068, 6290772, 12582228, 25167188, 50333012, 100660564, 201323860, 402658644, 805311828, 1610601812, 3221214548
OFFSET
0,3
FORMULA
From R. J. Mathar, Apr 25 2008: (Start)
G.f.: x*(1-x+2*x^2+2*x^4)/((x-1)*(2*x-1)*(2*x^2+1)).
a(n) = 3*2^(n-2)-(-1)^[(n+1)/2]*A016116(n+1)/6-4/3, n > 1. (End)
CROSSREFS
Sequence in context: A009884 A032023 A094837 * A350881 A018114 A356695
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Apr 01 2008
STATUS
approved