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A123256
Dimension of the invariant subspace in modules over the symmetric groups S_n of dimension n*(n+1)^(n-1).
1
1, 2, 3, 6, 10, 24, 49, 121, 289, 730, 1843, 4794, 12487
OFFSET
2,2
COMMENTS
No simple formula known, just a complicated sum over partitions.
Empirically a(n+1) = sum( d divides n, A000081(d) ), this holds for the terms given. If true, this sequences starts 1, 2, 3, 6, 10, 24, 49, 121, 289, 730, 1843, 4794, 12487, 33023, 87823, 235502, 634848, 1721469, 4688677, 12826962, 35221883, 97057025, 268282856, 743729893, 2067174655, ... . - Joerg Arndt, Sep 03 2015
EXAMPLE
a(5)=6 from the module 2 s[1, 1, 1, 1, 1] + 9 s[2, 1, 1, 1] + 14 s[2, 2, 1] + 14 s[3, 1, 1] + 14 s[3,2] + 13 s[4, 1] + 6 s[5].
CROSSREFS
Sequence in context: A152536 A185164 A124345 * A111275 A298537 A272079
KEYWORD
nonn,more
AUTHOR
F. Chapoton, Oct 09 2006
STATUS
approved