37923176863
domain: N
Appears in sequences
- Number of words of length 2n-1 generated by the two letters s and t that reduce to the identity 1 by using the relations sssssss=1, tt=1 and stst=1. The generators s and t along with the three relations generate the 14-element dihedral group D7.at n=19A072844
- a(n) = Sum_{k=0..n} binomial(7*n+3,7*k+1).at n=5A387817