OFFSET
1,5
COMMENTS
This notion of rank is closely related to the Erdős-Selfridge classification of primes.
LINKS
T. D. Noe, Table of n, a(n) for n=1..10000
FORMULA
MATHEMATICA
rank[1]=0; rank[2]=0; rank[3]=1;
SetAttributes[rank, Listable];
rank[p_] := rank[p] = 1+Min[Max@@rank[First/@FactorInteger[p-1]], Max@@rank[First/@FactorInteger[p+1]]]; rank[Prime[Range[100]]]
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, May 28 2010
STATUS
approved