A318837 - OEIS

%I #9 Jul 27 2024 15:56:20

%S 1,2,2,2,2,3,2,3,3,4,2,5,2,6,7,8,2,9,2,7,10,11,2,12,4,13,9,10,2,14,2,

%T 15,16,17,18,19,2,20,21,22,2,23,2,16,24,25,2,26,6,27,28,21,2,29,30,31,

%U 32,33,2,34,2,35,36,37,38,39,2,28,40,41,2,42,2,43,44,32,45,46,2,47,29,48,2,49,50,51,52,53,2,54,55,40,56,57,58,59,2,60,61,44,2

%N Restricted growth sequence transform of A318836.

%H Antti Karttunen, <a href="/A318837/b318837.txt">Table of n, a(n) for n = 1..65537</a>

%F For all i, j: a(i) = a(j) => A062790(i) = A062790(j).

%o (PARI)

%o up_to = 65537;

%o rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };

%o A007431(n) = sumdiv(n,d,moebius(n/d)*eulerphi(d));

%o A318836(n) = { my(m=1); fordiv(n,d,if((d<n)&&(A007431(d)!=0),m *= prime(A007431(d)))); (m); }; \\

%o v318837 = rgs_transform(vector(up_to,n,A318836(n)));

%o A318837(n) = v318837[n];

%Y Cf. A007431, A062790, A318836.

%K nonn

%O 1,2

%A _Antti Karttunen_, Sep 05 2018