A155139 Primes p such that both p-+3 are not squarefree.

47, 53, 101, 239, 347, 353, 487, 547, 647, 653, 683, 719, 853, 947, 953, 1061, 1153, 1213, 1277, 1447, 1453, 1553, 1663, 1669, 1693, 1697, 1747, 1753, 1847, 2053, 2153, 2251, 2347, 2447, 2647, 2659, 2741, 2753, 2887, 2953, 3041, 3253, 3347, 3359, 3433

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Jan 21 2009

Keywords

• nonn

Comments

47-3=44=2^2*11, 47+3=50=2*5^2, ...

Links

• John Cerkan, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A153213, A049282.

Programs

Mathematica

<Harvey P. Dale, May 01 2012 *)

PARI

lista(nn) = forprime(p=3, nn, if (! issquarefree(p-3) && ! issquarefree(p+3), print1(p, ", "))); \\ Michel Marcus, Jul 05 2016