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A262676 Number of nonzero even numbers encountered when iterating A049820 starting from n: a(0) = 0 and for n >= 1, a(n) = (1-A000035(n)) + a(A049820(n)).

%I A262676 #9 Oct 03 2015 08:44:10
%S A262676 0,0,1,0,1,0,2,0,2,2,3,2,3,2,4,2,3,2,4,2,5,2,5,2,4,5,6,2,6,2,6,2,7,2,
%T A262676 7,2,3,2,8,2,8,2,8,2,9,2,9,2,9,9,10,2,10,2,10,2,10,2,11,2,10,2,12,2,3,
%U A262676 2,12,2,13,2,13,2,11,2,14,2,14,2,14,2,14,14,15,14,12,14,16,14,15,14,15,14,17,14,16,14,13,14,18,14,15,14,17
%N A262676 Number of nonzero even numbers encountered when iterating A049820 starting from n: a(0) = 0 and for n >= 1, a(n) = (1-A000035(n)) + a(A049820(n)).
%C A262676 Number of even 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 even, but excludes the zero.
%H A262676 Antti Karttunen, <a href="/A262676/b262676.txt">Table of n, a(n) for n = 0..10080</a>
%H A262676 A. Karttunen, <a href="https://oeis.org/plot2a?name1=A262676&amp;name2=A262677&amp;tform1=untransformed&amp;tform2=untransformed&amp;shift=0&amp;radiop1=ratio&amp;drawpoints=true">Ratio a(n)/A262677(n) drawn with the help of OEIS Plot2-script</a>
%F A262676 a(0) = 0; for n >= 1, a(n) = (1-A000035(n)) + a(A049820(n)).
%F A262676 Other identities. For all n >= 0:
%F A262676 A155043(n) = a(n) + A262677(n).
%o A262676 (Scheme, with memoization-macro definec)
%o A262676 (definec (A262676 n) (if (zero? n) n (+ (- 1 (A000035 n)) (A262676 (A049820 n)))))
%Y A262676 Cf. A000005, A000035, A049820, A155043, A262677, A262680.
%K A262676 nonn
%O A262676 0,7
%A A262676 _Antti Karttunen_, Oct 03 2015