252000000

Appears in sequences

• a(n) = number of unicyclic connected simple graphs whose cycle has length 4.at n=6A065889
• Triangle T(n,k) of numbers of connected (unicyclic) graphs with unique cycle of length k (3<=k<=n), on n labeled nodes.at n=29A098909
• a(n)=2a(n-1) but when sum of digits of 2a(n-1) is greater than 9 take a(n) = largest number < 2a(n-1) which has sum of digits = 9.at n=28A140134
• Triangle T(n,k), n>=0, 0<=k<=n, read by rows: T(n,k) = number of simple graphs on n labeled nodes with k edges where each maximally connected subgraph consists of a single node or has a unique cycle of length 4.at n=65A144209
• Number of endofunctions on [n] where the largest cycle length equals 6.at n=4A246216