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A126947
The sequence c[n] defined in A126940.
2
0, 2, 4, 12, 42, 132, 414, 1320, 4198, 13322, 42308, 134392, 426832, 1355612, 4305518, 13674594, 43431194, 137939776, 438104256, 1391442706, 4419296770, 14035924512, 44578852058, 141584833642, 449681053086, 1428211232054, 4536075755738, 14406820782444
OFFSET
0,2
COMMENTS
Linear recurrence and empirical g.f confirmed for more terms. - Ray Chandler, Mar 07 2024
FORMULA
Empirical g.f.: -2*x*(x^2+1) / (x^6+4*x^5+4*x^4+7*x^3+x^2+2*x-1). - Colin Barker, Apr 08 2013
MATHEMATICA
LinearRecurrence[{2, 1, 7, 4, 4, 1}, {0, 2, 4, 12, 42, 132}, 30] (* Harvey P. Dale, Jul 25 2024 *)
CROSSREFS
Sequence in context: A244035 A340025 A126942 * A188494 A202668 A200222
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 18 2007
STATUS
approved