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a(n) = gcd(n, pi(n)) where pi is A000720.
3

%I #11 Apr 23 2018 08:38:10

%S 1,1,1,2,1,3,1,4,1,2,1,1,1,2,3,2,1,1,1,4,1,2,1,3,1,1,9,1,1,10,1,1,11,

%T 1,1,1,1,2,3,4,1,1,1,2,1,2,1,3,1,5,3,1,1,2,1,8,1,2,1,1,1,2,9,2,1,6,1,

%U 1,1,1,1,4,1,1,3,1,7,3,1,2,1,2,1,1,1,1,1,1,1,6,1,4,3,2,1,24,1,1,1,25,1,2,1

%N a(n) = gcd(n, pi(n)) where pi is A000720.

%H Ivan Neretin, <a href="/A087267/b087267.txt">Table of n, a(n) for n = 1..10000</a>

%t Table[GCD[w, PrimePi[w]], {w, 1, 256}]

%o (PARI) a(n) = gcd(n, primepi(n)); \\ _Michel Marcus_, Apr 22 2018

%Y Cf. A007053, A000720, A087266, A057809.

%K nonn

%O 1,4

%A _Labos Elemer_, Sep 16 2003