|
%I #5 Oct 03 2015 08:44:20
%S 0,1,0,2,1,3,0,4,1,1,0,2,0,3,0,3,2,4,0,5,0,5,0,6,2,1,0,7,0,8,0,9,0,9,
%T 0,10,7,11,0,11,0,12,0,13,0,12,0,13,0,1,0,14,0,15,0,15,0,16,0,17,0,18,
%U 0,17,16,19,0,20,0,20,0,21,0,22,0,21,0,23,0,24,0,1,0,2,0,2,0,3,0,4,0,4,0,5,0,5,0,6,0,6,4,7,0,8,0,7,0,8
%N Number of odd numbers encountered when iterating A049820 starting from n: a(0) = 0 and for n >= 1, a(n) = A000035(n) + a(A049820(n)).
%C Number of odd numbers encountered before zero is reached when starting from k = n and repeatedly applying the map that replaces k by k - d(k), where d(k) is the number of divisors of k (A000005). This count includes n itself if it is odd.
%H Antti Karttunen, <a href="/A262677/b262677.txt">Table of n, a(n) for n = 0..10080</a>
%F a(0) = 0; for n >= 1, a(n) = A000035(n) + a(A049820(n)).
%F Other identities. For all n >= 0:
%F A155043(n) = A262676(n) + a(n).
%o (Scheme, with memoization-macro definec)
%o (definec (A262677 n) (if (zero? n) n (+ (A000035 n) (A262677 (A049820 n)))))
%Y Cf. A000005, A000035, A049820, A155043, A262676, A262680.
%K nonn
%O 0,4
%A _Antti Karttunen_, Oct 03 2015
|
