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a(n) = least k > n such that phi(k) < phi(n), if such a k exists; otherwise a(n) = 0.
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%I #7 Jan 03 2017 02:16:52

%S 0,0,0,0,6,0,8,0,10,0,12,0,14,0,18,18,18,0,20,0,22,24,24,0,26,30,28,

%T 30,30,0,32,36,34,36,36,0,38,40,40,42,42,0,44,48,46,48,48,0,50,54,52,

%U 54,54,60,56,60,58,60,60,0,62,66,64,66,66,0,68,70,70,0,72,0,74,78,76,78,78,0

%N a(n) = least k > n such that phi(k) < phi(n), if such a k exists; otherwise a(n) = 0.

%C If a(n) = 0, then from n onwards, phi will not go below its value at n.

%C The first odd term in this sequence is a(314) = 315. - _Franklin T. Adams-Watters_, Oct 25 2006

%e a(2) = 0 since there is no k > 2 for which phi(k) < 1 = phi(2). a(5) = 6 since for k = 6, phi(6) = 2 < 4 = phi(5).

%Y Cf. A000010, A036912, A036913.

%K nonn

%O 1,5

%A _Joseph L. Pe_, Dec 20 2001

%E More terms from _Franklin T. Adams-Watters_, Oct 25 2006