

A055659


Number of (2,n)partitions of a chain of length n^3.


2



0, 15, 253, 1653, 6786, 21115, 54615, 123753, 253828, 481671, 858705, 1454365, 2359878, 3692403, 5599531, 8264145, 11909640, 16805503, 23273253, 31692741, 42508810, 56238315, 73477503, 94909753, 121313676, 153571575, 192678265
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OFFSET

1,2


COMMENTS

a (k,n)partition of a chain C is a chain of k intervals of C of length n.


LINKS



FORMULA

a(n) = (1/2)*(n1)*(n^2+n1)*(n^32*n+2).


EXAMPLE

a(2)=15 because in the linearly ordered set {1,..,8} we can choose in 15 ways 2 successive blocks of 2 consecutive elements.


PROG

(Magma) [(1/2) *(n1)*(n^2+n1)*(n^32*n+2): n in [1..35]]; // Vincenzo Librandi, Jun 30 2011
(PARI) a(n) = (n1)*(n^2+n1)*(n^32*n+2)/2; \\ Altug Alkan, Oct 04 2018


CROSSREFS



KEYWORD

nonn


AUTHOR

Paolo Dominici (pl.dm(AT)libero.it), Jun 07 2000


STATUS

approved



