Search: id:A117515 Results 1-1 of 1 results found. %I A117515 %S A117515 1,2,6,72,1240,33360 %N A117515 Number of ways of arranging 2n tokens in a row, with 2 copies of each token from 1 through n, such that between every pair of tokens labeled i (i=1..n) there is exactly one taken labeled (i+1 mod n). %Y A117515 Cf. A002105, A117514, A117513. %Y A117515 Sequence in context: A152885 A052613 A156493 this_sequence A085865 A061296 A019993 %Y A117515 Adjacent sequences: A117512 A117513 A117514 this_sequence A117516 A117517 A117518 %K A117515 nonn %O A117515 1,2 %A A117515 Nan Zang (nzang(AT)cs.ucsd.edu), Apr 28 2006 Search completed in 0.001 seconds