A049229 Primes p such that p-2 is not squarefree.

11, 29, 47, 83, 101, 127, 137, 149, 173, 191, 227, 263, 277, 281, 317, 353, 389, 443, 461, 479, 509, 541, 569, 577, 587, 607, 641, 659, 677, 727, 821, 827, 839, 857, 877, 911, 929, 947, 977, 983, 1019, 1031, 1091, 1109, 1129, 1163, 1181, 1217, 1277, 1289

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Comments

This sequence is infinite and its relative density in the sequence of the primes is equal to 1 - 2 * Product_{p prime} (1-1/(p*(p-1))) = 1 - 2 * A005596 = 0.252088... - Amiram Eldar, Feb 27 2021

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005596, A013929, A049231, A049232.

Programs

Mathematica

Select[Prime[Range[2,300]],!SquareFreeQ[#-2]&] (* Harvey P. Dale, Nov 14 2012 *)

PARI

isok(p) = (p>2) && isprime(p) && !issquarefree(p-2); \\ Michel Marcus, May 14 2018