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A108208
a(n) = 4*(n-1)*a(n-1) -2*(n-1)*a(n-2), with a(0)=0, a(1)=2.
0
0, 2, 8, 56, 624, 9536, 184480, 4313088, 118183744, 3712870400, 131536027008, 5187183672320, 225342288987904, 10691937463283712, 550121848577067520, 30507449271343837184, 1813943300823318205440, 115116132876009362358272
OFFSET
0,2
COMMENTS
This is also the negative of the (1,2) element of the product matrix after multiplying the unit matrix from the
left by the matrices (0,-2;j-1,4j-4) in the order j=2 to n.
MATHEMATICA
M[n_] := {{0, -2}, {(n - 1), 4*(n - 1)}} v[1] = {0, 1} v[n_] := v[n] = M[n].v[n - 1] a = Table[Abs[v[n][[1]]], {n, 1, 25}]
RecurrenceTable[{a[0]==0, a[1]==2, a[n]==4(n-1)a[n-1]-2(n-1)a[n-2]}, a, {n, 20}] (* Harvey P. Dale, Apr 11 2020 *)
CROSSREFS
Cf. A000166.
Sequence in context: A243953 A005439 A128814 * A203199 A348875 A302999
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula, Jun 15 2005
EXTENSIONS
Definition replaced by recurrence by the Associate Editors of the OEIS, Sep 28 2009
STATUS
approved