21242341

Appears in sequences

• Expansion of 1/((1-x)^7 - x^7).at n=21A049017
• Number of words of length 2n generated by the two letters s and t that reduce to the identity 1 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=14A072266
• Number of walks of length n between two adjacent nodes in the cycle graph C_7.at n=27A094052
• p-INVERT of (1,1,1,1,1,...), where p(S) = 1 - S^7.at n=27A290994
• a(n) = Sum_{k=0..floor(n/7)} binomial(n,7*k).at n=27A306852
• Cogrowth sequence for the 14-element dihedral group D7 = <S,T | S^7, T^2, (ST)^2>.at n=28A377573