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A023571 Least odd prime divisor of p(n)-3, or 1 if p(n)-3 is a power of 2. 0

%I

%S 1,1,1,1,1,5,7,1,5,13,7,17,19,5,11,5,7,29,1,17,5,19,5,43,47,7,5,13,53,

%T 5,31,1,67,17,73,37,7,5,41,5,11,89,47,5,97,7,13,5,7,113,5,59,7,31,127,

%U 5,7,67,137,139,5,5,19,7,5,157,41,167,43,173,5,89,7,5,47,5

%N Least odd prime divisor of p(n)-3, or 1 if p(n)-3 is a power of 2.

%t Join[{1,1},Table[If[IntegerQ[Log[2,n-3]],1,Select[ Transpose[ FactorInteger[ n-3]][[1]],#>2&][[1]]],{n,Prime[Range[3,80]]}]] (* _Harvey P. Dale_, Jul 16 2016 *)

%K nonn

%O 1,6

%A _Clark Kimberling_

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Last modified August 18 16:18 EDT 2022. Contains 356215 sequences. (Running on oeis4.)