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If A262686(n) = 0, a(n) = 1, otherwise a(n) = 1 + a(A262686(n)), where A262686(n) = largest number k such that k - d(k) = n, or 0 if no such number exists, and d(n) = the number of divisors of n (A000005).
4

%I #8 Dec 03 2015 04:36:17

%S 13,3,12,3,2,2,11,1,1,4,3,3,10,1,2,6,2,5,9,1,1,4,8,3,1,1,3,2,1,2,7,7,

%T 2,1,6,6,1,1,7,5,1,2,5,1,2,4,4,3,6,1,1,2,1,3,3,1,1,2,2,5,5,4,4,1,1,3,

%U 1,1,1,2,3,4,4,3,1,1,3,2,5,1,2,2,4,4,3,1,3,3,1,5,4,2,2,4,3,6,2,5,1,3,1

%N If A262686(n) = 0, a(n) = 1, otherwise a(n) = 1 + a(A262686(n)), where A262686(n) = largest number k such that k - d(k) = n, or 0 if no such number exists, and d(n) = the number of divisors of n (A000005).

%C See comments at A264970.

%H Antti Karttunen, <a href="/A264971/b264971.txt">Table of n, a(n) for n = 0..10000</a>

%F If A060990(n) = 0, a(n) = 1, otherwise a(n) = 1 + a(A262686(n)).

%F Other identities. For all n >= 0:

%F a(n) = 1 + A264970(n).

%o (Scheme, with memoization-macro definec)

%o (definec (A264971 n) (cond ((A262686 n) => (lambda (lad) (if (zero? lad) 1 (+ 1 (A264971 lad)))))))

%Y Cf. A000005, A049820, A060990, A262686.

%Y One more than A264970.

%Y Number of significant terms on row n of A263271.

%K nonn

%O 0,1

%A _Antti Karttunen_, Nov 29 2015