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A049282
Primes p such that both p-2 and p+2 are squarefree.
10
3, 5, 13, 17, 19, 31, 37, 41, 53, 59, 67, 71, 89, 103, 107, 109, 113, 131, 139, 157, 163, 179, 181, 193, 197, 199, 211, 229, 233, 239, 251, 257, 269, 271, 283, 293, 307, 311, 337, 347, 379, 383, 397, 401, 409, 419, 431, 433, 449, 463, 467, 487, 491, 499, 503
OFFSET
1,1
FORMULA
Intersection of A049231 and A049233.
EXAMPLE
37 is here because neither 37+2 nor 37-2 is divisible by squares.
MAPLE
with(numtheory): A049282:=n->`if`(isprime(n) and issqrfree(n-2) and issqrfree(n+2), n, NULL): seq(A049282(n), n=1..10^3); # Wesley Ivan Hurt, Jun 25 2016
MATHEMATICA
lst={}; Do[p=Prime[n]; If[SquareFreeQ[p-2]&&SquareFreeQ[p+2], AppendTo[lst, p]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Dec 20 2008 *)
PROG
(PARI) lista(nn) = forprime(p=2, nn, if (issquarefree(p-2) && issquarefree(p+2), print1(p, ", "))); \\ Michel Marcus, Jun 22 2016
CROSSREFS
Sequence in context: A045411 A184796 A180944 * A003625 A105900 A260191
KEYWORD
nonn
AUTHOR
STATUS
approved