a(1) = 1; a(n+1) = Sum_{d|n} tau(d)*a(d), where tau = number of divisors (A000005).
A307793
a(1) = 1; a(n+1) = Sum_{d|n} tau(d)*a(d), where tau = number of divisors (A000005).
Terms
- a(0) =1a(1) =1a(2) =3a(3) =7a(4) =24a(5) =49a(6) =205a(7) =411a(8) =1668a(9) =5011a(10) =20095a(11) =40191a(12) =241372a(13) =482745a(14) =1931393a(15) =7725627a(16) =38629803a(17) =77259607a(18) =463562851a(19) =927125703a(20) =5562774334a(21) =22251097753a(22) =89004431205a(23) =178008862411
External references
- oeis: A307793