21192

Appears in sequences

• Triangle read by rows: T(n,k) (n >= 2, k >= 0) is the number of non-crossing connected graphs on n nodes on a circle, having k triangles. Rows are indexed 2,3,4,...; columns are indexed 0,1,2,....at n=23A089435
• Number of nX2 1..3 arrays containing at least one of each value, and all equal values connected.at n=8A166756
• Index of first occurrence of 2n in A031883, or 0 if 2n never occurs in A031883 = first differences of lucky numbers A000959.at n=34A181558
• Upper Beatty array of sqrt(2).at n=47A182638
• Number of sequences of 2's and 3's of length n with curling number 3.at n=16A217212
• a(n) = Sum_{k=1..floor(n/2)} k * (n-k) * floor((n-k)/k).at n=43A339804
• Non-1-tough simplicial polyhedra with n nodes.at n=5A342971
• a(n) = Sum_{d|n} n^phi(d).at n=11A345893