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A078062
Expansion of (1-x)/(1+2*x+2*x^3).
0
1, -3, 6, -14, 34, -80, 188, -444, 1048, -2472, 5832, -13760, 32464, -76592, 180704, -426336, 1005856, -2373120, 5598912, -13209536, 31165312, -73528448, 173475968, -409282560, 965622016, -2278195968, 5374957056, -12681158144, 29918708224, -70587330560, 166536977408
OFFSET
0,2
FORMULA
a(n) = (-1)^n*Sum_{k=0..n} C(n-k,floor(k/2))*2^(n-k). - Paul Barry, Oct 20 2009
a(0) = 1, a(1) = -3, a(2) = 6, a(n) = -2*a(n-1) - 2*a(n-3) for n > 2. - Jinyuan Wang, Apr 07 2020
PROG
(PARI) Vec((1-x)/(1+2*x+2*x^3) + O(x^50)) \\ Jinyuan Wang, Apr 07 2020
CROSSREFS
Sequence in context: A003477 A368983 A339600 * A275873 A018017 A184785
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved