A155141 Primes p such that both p-+4 are squarefree.

2, 3, 7, 11, 17, 19, 37, 43, 47, 61, 73, 83, 89, 97, 101, 107, 109, 127, 137, 163, 181, 191, 197, 199, 223, 227, 233, 251, 263, 269, 277, 281, 307, 313, 317, 331, 349, 353, 389, 397, 431, 433, 439, 443, 449, 457, 461, 467, 487, 523, 541, 547, 557, 569, 577, 587

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, 6!}]; lst
Select[Prime[Range[150]], AllTrue[#+{4, -4}, SquareFreeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 15 2016 *)

Prog

(PARI) lista(nn) = forprime(p=2, nn, if (issquarefree(p-4) && issquarefree(p+4), print1(p, ", "))); \\ Michel Marcus, Jul 06 2016

Crossrefs

Cf. A153213, A049282, A155139, A155140, A155142.

Sequence in context: A161185 A226993 A235482 * A127944 A294677 A274161

Adjacent sequences: A155138 A155139 A155140 * A155142 A155143 A155144

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jan 21 2009

Status

approved