A103666 Primes p such that the largest prime divisor of p-1 is less than the largest prime divisor of p+1.

5, 13, 17, 19, 37, 41, 43, 61, 67, 73, 97, 101, 109, 113, 137, 151, 157, 163, 181, 193, 197, 211, 229, 241, 251, 257, 271, 277, 281, 283, 313, 331, 337, 353, 379, 397, 401, 409, 421, 433, 443, 457, 463, 487, 491, 521, 523, 541, 547, 577, 601, 613, 617, 631

Offset: 1

Author

Hugo Pfoertner, Feb 19 2005

Keywords

• nonn

Examples

			a(1)=5 because the largest prime divisor of 4 is less than the largest prime divisor of 6.
		

Links

• Karl Hovekamp, Table of n, a(n) for n=1..39168

Crossrefs

Cf. A023503 greatest prime divisor of n-th prime - 1, A023509 greatest prime divisor of n-th prime + 1, A103667.

Programs

Mathematica

Select[Prime[Range[2,200]],Max[Transpose[FactorInteger[#-1]][[1]]]< Max[Transpose[FactorInteger[#+1]][[1]]]&]  (* Harvey P. Dale, Apr 26 2011 *)