A155140 - OEIS

A155140

Primes p such that both p-+4 are not squarefree.

293, 347, 571, 829, 1021, 1229, 1327, 1373, 1471, 1621, 2111, 2129, 2371, 2531, 2579, 2879, 2887, 3181, 3271, 3929, 4621, 4801, 4909, 5279, 5333, 5521, 5639, 5683, 5827, 6133, 6421, 6521, 6709, 6863, 6871, 7079, 7321, 7529, 7591, 8179, 8221, 8429, 8963

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

MATHEMATICA

<<NumberTheory`NumberTheoryFunctions` lst={}; Do[p=Prime[n]; If[ !SquareFreeQ[p-4]&&!SquareFreeQ[p+4], AppendTo[lst, p]], {n, 7!}]; lst

Select[Prime[Range[1200]], NoneTrue[#+{4, -4}, SquareFreeQ]&] (* Harvey P. Dale, Jul 17 2024 *)

PROG

(PARI) lista(nn) = forprime(p=2, nn, if (! issquarefree(p-4) && ! issquarefree(p+4), print1(p, ", "))); \\ Michel Marcus, Jul 05 2016

CROSSREFS

Cf. A153213, A049282, A155139, A155141, A155142.