A117514 - cp's OEIS frontend

A117514 Number of ways of arranging 2n tokens in a row, with 2 copies of each token from 1 through n, such that the first token is a 1 and between every pair of tokens labeled i (i=1..n) there is exactly one taken labeled (i+1 mod n).

%I A117514 #2 Feb 27 2009 03:00:00
%S A117514 1,1,2,18,248,5560,174752
%N A117514 Number of ways of arranging 2n tokens in a row, with 2 copies of each token from 1 through n, such that the first token is a 1 and between every pair of tokens labeled i (i=1..n) there is exactly one taken labeled (i+1 mod n).
%Y A117514 Cf. A002105, A117513, A117515.
%K A117514 nonn
%O A117514 1,3
%A A117514 Nan Zang (nzang(AT)cs.ucsd.edu), Apr 28 2006

cp's OEIS Frontend

A117514 Number of ways of arranging 2n tokens in a row, with 2 copies of each token from 1 through n, such that the first token is a 1 and between every pair of tokens labeled i (i=1..n) there is exactly one taken labeled (i+1 mod n).