OFFSET
1,3
COMMENTS
Also the number of non-splitable set partitions (see Bergeron et al. reference) of length <=5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..500
N. Bergeron, C. Reutenauer, M. Rosas and M. Zabrocki, Invariants and Coinvariants of the Symmetric Group in Noncommuting Variables, arXiv:math/0502082 [math.CO], 2005.
N. Bergeron, C. Reutenauer, M. Rosas and M. Zabrocki, Invariants and Coinvariants of the Symmetric Group in Noncommuting Variables, Canad. J. Math. 60 (2008), no. 2, 266-296.
M. C. Wolf, Symmetric functions of noncommutative elements, Duke Math. J. 2 (1936), 626-637.
Index entries for linear recurrences with constant coefficients, signature (10,-32,37,-11).
FORMULA
MAPLE
a:= n-> (Matrix([[6, 2, 1, 1]]). Matrix(4, (i, j)-> if i=j-1 then 1 elif j=1 then [10, -32, 37, -11][i] else 0 fi)^(n-1))[1, 4]: seq(a(n), n=1..30); # Alois P. Heinz, Sep 05 2008
MATHEMATICA
LinearRecurrence[{10, -32, 37, -11}, {1, 1, 2, 6}, 30] (* Jean-François Alcover, Jan 08 2016 *)
PROG
(Magma) I:=[1, 1, 2, 6]; [n le 4 select I[n] else 10*Self(n-1)-32*Self(n-2)+37*Self(n-3)-11*Self(n-4): n in [1..30]]; // Vincenzo Librandi, Jan 09 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Mike Zabrocki, Oct 24 2006
STATUS
approved