A332224 - OEIS

%I #8 Feb 13 2020 02:52:59

%S 1,2,4,3,4,8,8,4,5,10,8,12,6,16,16,5,10,7,12,14,32,20,16,16,5,14,24,

%T 24,8,40,32,6,32,12,32,10,12,16,24,18,14,64,16,28,14,40,32,20,13,11,

%U 40,34,12,32,40,32,48,18,16,56,10,64,40,7,28,80,36,12,64,80,40,34,22,26,20,40,64,56,48,22,17,12,28,96,24,68,32,36,18

%N a(n) = A087808(sigma(n)).

%H Antti Karttunen, <a href="/A332224/b332224.txt">Table of n, a(n) for n = 1..16383</a>

%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

%F a(n) = A087808(A000203(n)).

%t Block[{s = DivisorSigma[1, Range[90]], t}, t = Nest[Append[#1, If[EvenQ[#2], 2 #1[[#2/2 + 1]], #1[[(#2 - 1)/2 + 1]] + 1]] & @@ {#, Length@ #} &, {0}, Max@ s]; t[[Most@ s + 1]] ] (* _Michael De Vlieger_, Feb 12 2020 *)

%o (PARI)

%o A087808(n) = if(n<1, 0, if(n%2==0, 2*A087808(n/2), A087808((n-1)/2)+1));

%o A332224(n) = A087808(sigma(n));

%Y Cf. A000203, A087808, A332225.

%Y Cf. also A324293.

%K nonn

%O 1,2

%A _Antti Karttunen_, Feb 12 2020