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%I #5 Jan 03 2013 12:39:31
%S 0,1,1,1,2,2,1,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,3,2,2,
%T 2,2,3,2,2,3,2,2,2,2,2,2,2,2,3,3,3,2,2,2,1,3,2,2,3,2,3,2,2,2,3,3,3,2,
%U 3,2,3,2,3,2,2,2,3,3,2,2,2,2,2,2,3,3,2,3,3,3,3,2,2,2,2,2,2,3,3
%N Rank of n-th prime as defined in A177854.
%C This notion of rank is closely related to the Erdős-Selfridge classification of primes.
%H T. D. Noe, <a href="/A169818/b169818.txt">Table of n, a(n) for n=1..10000</a>
%F a(A000720(A141453(n)))=1 n>1. [From _R. J. Mathar_, May 28 2010]
%t rank[1]=0; rank[2]=0; rank[3]=1;
%t SetAttributes[rank,Listable];
%t rank[p_] := rank[p] = 1+Min[Max@@rank[First/@FactorInteger[p-1]], Max@@rank[First/@FactorInteger[p+1]]]; rank[Prime[Range[100]]]
%Y For records see A177854.
%K nonn
%O 1,5
%A _T. D. Noe_, May 28 2010
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