524324domain: NAppears in sequencesa(n) = Sum_{d|n} phi(d)*2^(n/d).at n=19A053635a(n) = Sum_{odd d|n} phi(d)*2^(n/d).at n=19A053636Number of partitions of the graph G_n (defined below) into "strokes".at n=18A131520a(n) = Sum_{k=0..n} binomial(n,k) * gcd(n,k).at n=18A159553a(n) = Sum_{d|n} 2^d*phi(2*n/d).at n=18A306898