A153213 Primes p such that both p-2 and p+2 are not squarefree.

2, 47, 173, 277, 727, 839, 929, 1181, 1423, 1447, 1523, 1627, 1811, 1847, 1861, 1973, 2207, 2297, 2423, 2693, 3323, 3701, 3719, 3877, 4327, 4363, 4457, 4673, 4691, 4903, 5227, 5573, 5821, 5927, 6173, 6221, 6323, 6473, 6577, 6653, 7027, 7103, 7477, 7823

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Dec 20 2008

Keywords

• nonn

Links

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

Crossrefs

Cf. A049282, A049097, A039787, A075432, A153207, A153208, A153209, A153210.

Programs

Mathematica

lst={};Do[p=Prime[n];If[ !SquareFreeQ[p-2]&&!SquareFreeQ[p+2],AppendTo[lst,p]],{n,7!}];lst

PARI

is(n)=isprime(n) && !issquarefree(n-2) && !issquarefree(n+2) \\ Charles R Greathouse IV, Nov 05 2017