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a(n) = the smallest non-divisor h of n (1<h<n), or 0 if no such h exists.
4

%I #11 Oct 06 2015 01:47:09

%S 0,0,2,3,2,4,2,3,2,3,2,5,2,3,2,3,2,4,2,3,2,3,2,5,2,3,2,3,2,4,2,3,2,3,

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

%U 2,3,2,5,2,3,2,3,2,4,2,3,2,3,2

%N a(n) = the smallest non-divisor h of n (1<h<n), or 0 if no such h exists.

%C a(n) = A173540(n,1). - _Reinhard Zumkeller_, Oct 02 2015

%H Reinhard Zumkeller, <a href="/A199968/b199968.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007978(n) for n>=3.

%o (Haskell)

%o a199968 = head . a173540_row -- _Reinhard Zumkeller_, Oct 02 2015

%Y Cf. A199969 (the greatest non-divisor h of n (1<h<n)), A199970.

%Y Cf. A173540.

%K nonn

%O 1,3

%A _Jaroslav Krizek_, Nov 26 2011