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A103143
a(n) = a(n-1) + a(n-2) + 3*a(n-3), with a(0) = 1, a(1) = 0, a(2) = 1.
6
0, 0, 1, 1, 2, 6, 11, 23, 52, 108, 229, 493, 1046, 2226, 4751, 10115, 21544, 45912, 97801, 208345, 443882, 945630, 2014547, 4291823, 9143260, 19478724, 41497453, 88405957, 188339582, 401237898, 854795351, 1821051995, 3879561040, 8264999088, 17607716113
OFFSET
0,5
COMMENTS
Diagonal sums of the Pascal-(1,3,1) triangle A081578.
FORMULA
G.f.: 1/(1-x-x^2-3x^3).
MATHEMATICA
LinearRecurrence[{1, 1, 3}, {0, 0, 1}, 50] (* Vladimir Joseph Stephan Orlovsky, May 25 2011 *)
CROSSREFS
Sequence in context: A005999 A102429 A080012 * A005673 A084308 A067605
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jan 24 2005
EXTENSIONS
Name clarified by Michel Marcus, Aug 07 2022
STATUS
approved