57177120domain: NAppears in sequencesIf n | a(n) then a(n+1) = a(n)/(highest power of n that divides a(n)), otherwise a(n+1) = n*a(n); a(0) = 1.at n=17A065422Triangle read by rows: T(n,k) (n>=2, 1<=k<=n-1) is the number of unordered pairs of vertices at distances k in the odd graph O_n.at n=33A228308