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A118406
Unsigned row sums of triangle A118404.
2
1, 2, 2, 4, 4, 8, 14, 28, 52, 104, 206, 412, 820, 1640, 3278, 6556, 13108, 26216, 52430, 104860, 209716, 419432, 838862, 1677724, 3355444, 6710888, 13421774, 26843548, 53687092, 107374184, 214748366, 429496732, 858993460, 1717986920, 3435973838
OFFSET
0,2
FORMULA
G.f.: A(x) = (1 - 2*x^2 - 5*x^4)/(1-x^4)/(1-2*x).
MATHEMATICA
CoefficientList[Series[(1-2x^2-5x^4)/(1-x^4)/(1-2x), {x, 0, 40}], x] (* or *) LinearRecurrence[{2, 0, 0, 1, -2}, {1, 2, 2, 4, 4}, 40] (* Harvey P. Dale, Jul 29 2021 *)
PROG
(PARI) {a(n)=polcoeff((1 - 2*x^2 - 5*x^4)/(1-x^4)/(1-2*x+x*O(x^n)), n, x)}
CROSSREFS
Sequence in context: A287135 A276063 A247181 * A355811 A357214 A072488
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Apr 27 2006
STATUS
approved