A322940 a(n) = [x^n] (4*x^2 + x - 1)/(2*x^2 + 3*x - 1).
1, 2, 4, 16, 56, 200, 712, 2536, 9032, 32168, 114568, 408040, 1453256, 5175848, 18434056, 65653864, 233829704, 832796840, 2966049928, 10563743464, 37623330248, 133997477672, 477239093512, 1699712235880, 6053614894664, 21560269155752, 76788037256584
Offset: 0
Keywords
Links
- Index entries for linear recurrences with constant coefficients, signature (3, 2).
Programs
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Maple
a := proc(n) option remember; `if`(n < 3, [1, 2, 4][n+1], 3*a(n-1) + 2*a(n-2)) end: seq(a(n), n=0..26);
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Mathematica
Join[{1}, LinearRecurrence[{3, 2}, {2, 4}, 26]] (* Jean-François Alcover, Jul 13 2019 *)