A072012 - OEIS

%I #11 Nov 21 2021 07:34:34

%S 1,2,1,4,5,2,7,8,1,10,1,4,7,14,5,16,17,2,19,20,7,2,5,8,25,14,1,28,29,

%T 10,31,32,1,34,35,4,15,38,7,40,41,14,43,4,5,10,7,16,49,50,17,28,63,2,

%U 5,56,19,58,17,20,5,62,7,64,35,2,105,68,5,70,21,8,49,30

%N a(n) = A072010(A072010(n)).

%H Amiram Eldar, <a href="/A072012/b072012.txt">Table of n, a(n) for n = 1..10000</a>

%t b[n_] := If[n == 1, 1, Product[{p, e} = pe; Which[

%t      Mod[p, 4] == 1, p + 2,

%t      Mod[p, 4] == 3, p - 2,

%t      True, 2]^e, {pe, FactorInteger[n]}]];

%t a[n_] := b[b[n]];

%t Array[a, 100] (* _Jean-François Alcover_, Nov 21 2021 *)

%Y Cf. A072010, A072013.

%K nonn,mult

%O 1,2

%A _Reinhard Zumkeller_, Jun 05 2002