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A111407 a(n) = f(f(n+1)) - f(f(n)), where f(0) = 0 and f(m) = tau(m) = A000005(m) for m > 0.

%I A111407 #18 Jun 25 2022 21:43:42
%S A111407 1,1,0,0,0,1,-1,1,-1,1,-1,2,-2,1,0,-1,0,2,-2,2,-1,0,-1,2,-2,1,0,1,-2,
%T A111407 2,-2,2,-1,0,0,0,-1,1,0,1,-2,2,-2,2,0,-1,-1,2,-2,2,-1,1,-2,2,-1,1,-1,
%U A111407 0,-1,4,-4,1,1,-2,1,1,-2,2,-1,1,-2,4,-4,1,1,0,-1,1,-2,2,-2,1,-1,4,-3,0,0,1,-2,4,-3,1,-1,0,0,3,-4,2,0,-1,-1
%N A111407 a(n) = f(f(n+1)) - f(f(n)), where f(0) = 0 and f(m) = tau(m) = A000005(m) for m > 0.
%H A111407 Antti Karttunen, <a href="/A111407/b111407.txt">Table of n, a(n) for n = 0..20000</a>
%o A111407 (PARI)
%o A111407 f = numdiv;
%o A111407 a(n) = f(f(n+1)) - f(f(n));
%o A111407 concat([1], vector(166,n,a(n))) \\ _Joerg Arndt_, Jul 06 2013
%o A111407 (PARI)
%o A111407 f(n) = if(!n,n,numdiv(n));
%o A111407 A111407(n) = f(f(n+1)) - f(f(n)); \\ _Antti Karttunen_, Oct 07 2017
%Y A111407 Cf. A000005, A111405.
%Y A111407 First differences of A010553.
%K A111407 sign
%O A111407 0,12
%A A111407 _N. J. A. Sloane_, Nov 12 2005
%E A111407 Description clarified by _Antti Karttunen_, Oct 07 2017