A373246 - OEIS

%I #9 May 30 2024 16:57:36

%S 1,2,1,1,1,2,1,1,3,2,1,6,1,2,1,1,1,6,1,2,1,2,1,2,1,2,1,2,1,2,1,1,1,2,

%T 1,9,1,2,1,10,1,2,1,2,3,2,1,2,1,2,1,2,1,2,1,2,1,2,1,12,1,2,3,1,1,2,1,

%U 2,1,2,1,3,1,2,3,2,1,2,1,2,1,2,1,12,1,2,1,2,1,6,1,2,1,2,1,2,1,2,3,1,1,2,1,2,1

%N Greatest common divisor of n and its prime shadow: a(n) = gcd(n, A181819(n)).

%H Antti Karttunen, <a href="/A373246/b373246.txt">Table of n, a(n) for n = 1..65537</a>

%F a(n) = gcd(A181819(n), A373247(n)).

%F a(n) = A181819(n) / A373249(n).

%o (PARI)

%o A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));

%o A373246(n) = gcd(n, A181819(n));

%Y Cf. A181819, A373247, A373249.

%Y Cf. A325755 [numbers k for which a(k) = A181819(k)], A353566 (their characteristic function).

%K nonn

%O 1,2

%A _Antti Karttunen_, May 29 2024