cp's OEIS Frontend

A319698 Filter sequence combining A003557(n) [n divided by largest squarefree divisor of n] with A319697(n) [sum of even squarefree divisors of n].

%I A319698 #7 Oct 31 2018 21:54:28
%S A319698 1,2,1,3,1,4,1,5,6,7,1,8,1,9,1,10,1,11,1,12,1,13,1,14,15,16,17,18,1,
%T A319698 19,1,20,1,21,1,22,1,23,1,24,1,25,1,26,6,19,1,27,28,29,1,30,1,31,1,32,
%U A319698 1,33,1,34,1,25,6,35,1,36,1,37,1,36,1,38,1,39,15,40,1,41,1,42,43,44,1,45,1,46,1,47,1,48,1,34,1,36,1,49,1,50,6,51,1,52,1,53,1
%N A319698 Filter sequence combining A003557(n) [n divided by largest squarefree divisor of n] with A319697(n) [sum of even squarefree divisors of n].
%C A319698 Restricted growth sequence transform of ordered pair [A003557(n), A319697(n)].
%H A319698 Antti Karttunen, <a href="/A319698/b319698.txt">Table of n, a(n) for n = 1..65537</a>
%o A319698 (PARI)
%o A319698 up_to = 65537;
%o A319698 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 A319698 A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = f[i, 2]-1); factorback(f); }; \\ From A003557
%o A319698 A319697(n) = sumdiv(n, d, (!(d%2))*issquarefree(d)*d);
%o A319698 v319698 = rgs_transform(vector(up_to,n,[A003557(n),A319697(n)]));
%o A319698 A319698(n) = v319698[n];
%Y A319698 Cf. A003557, A319697.
%Y A319698 Cf also A291750, A291751.
%K A319698 nonn
%O A319698 1,2
%A A319698 _Antti Karttunen_, Oct 31 2018