121179domain: NAppears in sequencesa(1) = 2, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).at n=9A062094Number of nodes in graph BC(n,2) when the internal nodes are counted with multiplicity.at n=24A343994