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A297570
Number of nonisomorphic proper colorings of partition star graph using six colors.
7
6, 30, 90, 150, 210, 750, 750, 420, 2250, 1950, 3750, 3750, 756, 5250, 9750, 11250, 18750, 18750, 18750, 1260, 10500, 29250, 17550, 26250, 93750, 47250, 56250, 93750, 93750, 93750, 1980, 18900, 68250, 87750, 52500, 281250, 243750, 236250, 131250, 468750, 468750, 281250, 468750, 468750, 468750, 2970, 31500, 136500, 263250, 122850, 94500, 656250, 1218750, 708750, 1181250, 262500, 1406250, 1218750, 2343750, 1173750
OFFSET
0,1
COMMENTS
A partition star graph consists of a multiset of paths with lengths given by the elements of the partition attached to a distinguished root node. The ordering of the partitions is by traversing antichains in Young's lattice bottom to top, left to right. Isomorphism refers to the automorphisms of the star graph corresponding to the partition.
FORMULA
For a partition lambda we have the OCP: k Product_{p^v in lambda} C((k-1)^p+v-1, v). Here we have k=6.
EXAMPLE
Rows are:
6;
30;
90, 150;
210, 750, 750;
420, 2250, 1950, 3750, 3750;
756, 5250, 9750, 11250, 18750, 18750, 18750;
MAPLE
b:= (n, i)-> `if`(n=0, [6], `if`(i<1, [], [seq(map(x-> x*
binomial(5^i+j-1, j), b(n-i*j, i-1))[], j=0..n/i)])):
T:= n-> b(n$2)[]:
seq(T(n), n=0..10); # Alois P. Heinz, Jan 14 2018
MATHEMATICA
b[n_, i_] := If[n == 0, {6}, If[i<1, {}, Table[Map[Function[x, x*Binomial[ 5^i + j - 1, j]], b[n - i*j, i - 1]], {j, 0, n/i}]] // Flatten];
T[n_] := b[n, n];
Table[T[n], {n, 0, 10}] // Flatten (* Jean-François Alcover, Jan 17 2018, after Alois P. Heinz *)
CROSSREFS
Row sums give 6*A144069.
Row lengths give A000041.
Sequence in context: A094143 A217260 A009775 * A119536 A107394 A033487
KEYWORD
nonn,tabf
AUTHOR
Marko Riedel, Dec 31 2017
STATUS
approved