cp's OEIS Frontend

A319714 Filter sequence combining the largest proper divisor of n (A032742) with n's residue modulo 4 (A010873).

%I A319714 #11 Sep 26 2018 16:24:43
%S A319714 1,2,3,4,5,6,3,7,8,9,3,10,5,11,12,13,5,14,3,15,16,17,3,18,19,20,21,22,
%T A319714 5,23,3,24,25,26,27,28,5,29,30,31,5,32,3,33,34,35,3,36,16,37,38,39,5,
%U A319714 40,41,42,43,44,3,45,5,46,47,48,49,50,3,51,52,53,3,54,5,55,56,57,25,58,3,59,60,61,3,62,63,64,65,66,5,67,30,68,69,70,71,72,5,73
%N A319714 Filter sequence combining the largest proper divisor of n (A032742) with n's residue modulo 4 (A010873).
%C A319714 Restricted growth sequence transform of A286474, or equally, of A286473.
%H A319714 Antti Karttunen, <a href="/A319714/b319714.txt">Table of n, a(n) for n = 1..100000</a>
%o A319714 (PARI)
%o A319714 up_to = 100000;
%o A319714 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 A319714 A032742(n) = if(1==n,n,n/vecmin(factor(n)[,1]));
%o A319714 A286474(n) = if(1==n,n,(4*A032742(n) + (n % 4)));
%o A319714 v319714 = rgs_transform(vector(up_to,n,A286474(n)));
%o A319714 A319714(n) = v319714[n];
%Y A319714 Cf. A010873, A032742, A286473, A286474, A319704.
%K A319714 nonn
%O A319714 1,2
%A A319714 _Antti Karttunen_, Sep 26 2018