login
a(1) = a(2) = 1; for n > 2, a(n) = A000005(n) * a(A000005(n)), where A000005(n) gives the number of divisors of n.
3

%I #15 Nov 26 2018 17:13:34

%S 1,1,2,6,2,24,2,24,6,24,2,144,2,24,24,10,2,144,2,144,24,24,2,192,6,24,

%T 24,144,2,192,2,144,24,24,24,54,2,24,24,192,2,192,2,144,144,24,2,240,

%U 6,144,24,144,2,192,24,192,24,24,2,1728,2,24,144,14,24,192,2,144,24,192,2,1728,2,24,144,144,24,192,2,240,10,24,2,1728

%N a(1) = a(2) = 1; for n > 2, a(n) = A000005(n) * a(A000005(n)), where A000005(n) gives the number of divisors of n.

%H Antti Karttunen, <a href="/A320016/b320016.txt">Table of n, a(n) for n = 1..10080</a>

%F a(1) = a(2) = 1; for n > 2, a(n) = A000005(n) * a(A000005(n)), where A000005(n) gives the number of divisors of n.

%t Nest[Append[#1, #2 #1[[#2]] ] & @@ {#, DivisorSigma[0, Length@ # + 1]} &, {1, 1}, 82] (* _Michael De Vlieger_, Nov 25 2018 *)

%o (PARI) A320016(n) = if(n<=2,1,numdiv(n)*A320016(numdiv(n)));

%o (GAP) a:=[1,1];; for n in [3..100] do a[n]:=Tau(n)*a[Tau(n)]; od; a; # _Muniru A Asiru_, Nov 24 2018

%Y Cf. A000005, A036459, A060937.

%Y Cf. also A320009, A320118.

%K nonn

%O 1,3

%A _Antti Karttunen_, Nov 24 2018