206640

Appears in sequences

• Triangle of the numbers of unique-valued sequences of all lengths (from 1 to 2n-1) consisting of unit matrices (="matrix units") of order n.at n=31A114595
• Twin prime averages which are also the sum of the divisors of a triangular number.at n=36A166162
• Numbers with prime factorization pqrs^2t^4.at n=29A190384
• a(n) = (2^n - 1) * (3^(n+2) - 1) / 2.at n=6A253512
• a(n) = (n-1)! * Sum_{d|n} d^(n/d).at n=7A354851
• Triangular array read by rows. T(n,k) is the number of idempotent binary relations on [n] having no proper power primitive (A360718) with exactly k irreflexive points.at n=19A370208