206280

Appears in sequences

• Sum of the products of the first n prime pairs.at n=20A135232
• Practical numbers m with m-1 and m+1 both prime, and prime(m)-1 and prime(m)+1 both practical.at n=31A257922
• Triangle read by rows: T(n, k) = (Sum_{i=0..n-k} (-1)^i * binomial(n-k, i) * A007559(n-i)) * n! / ((n-k)! * A007559(k)) for 0 <= k <= n.at n=24A372921