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%I #27 Apr 22 2021 09:30:44
%S 1,2,2,3,6,6,3,6,6,4,10,10,12,30,30,12,30,30,4,10,10,12,30,30,12,30,
%T 30,5,14,14,15,42,42,15,42,42,20,70,70,60,210,210,60,210,210,20,70,70,
%U 60,210,210,60,210,210,5,14,14,15,42,42,15,42,42,20,70,70
%N a(n) = A289815(n) * A289816(n).
%C Each number k > 0 appears 2^omega(k) times (where omega = A001221).
%C a(A004488(n)) = a(n) for any n >= 0.
%C The number of distinct prime factors of a(n) equals the number of nonzero digits in the ternary representation of n.
%H Rémy Sigrist, <a href="/A289838/b289838.txt">Table of n, a(n) for n = 0..10000</a>
%e a(42) = A289815(42) * A289816(42) = 20 * 3 = 60.
%o (PARI) a(n) = { my (v=1);
%o for (o=2, oo,
%o if (n==0, return (v));
%o if (gcd(v, o)==1 && omega(o)==1,
%o if (n % 3, v *= o);
%o n \= 3;
%o );
%o );}
%o (Python)
%o from sympy import gcd, primefactors
%o def omega(n): return 0 if n==1 else len(primefactors(n))
%o def a(n):
%o v, o = 1, 2
%o while True:
%o if n==0: return v
%o if gcd(v, o)==1 and omega(o)==1:
%o if n%3: v*=o
%o n //= 3
%o o+=1
%o print([a(n) for n in range(101)]) # _Indranil Ghosh_, Aug 02 2017
%Y Cf. A001221, A004488, A289815, A289816.
%K nonn,base,look
%O 0,2
%A _Rémy Sigrist_, Jul 13 2017
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