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

1,1

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

Mathematica

<<NumberTheory`NumberTheoryFunctions`  (* needed with older versions *)
lst={}; Do[p=Prime[n]; If[ !SquareFreeQ[p-3]&&!SquareFreeQ[p+3], AppendTo[lst, p]], {n, 6!}]; lst
Select[Prime[Range[500]], !SquareFreeQ[#-3]&&!SquareFreeQ[#+3]&] (* Harvey P. Dale, May 01 2012 *)

Prog

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

Crossrefs

Cf. A153213, A049282.

Sequence in context: A128940 A243431 A141279 * A106279 A275022 A355601

Adjacent sequences: A155136 A155137 A155138 * A155140 A155141 A155142

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jan 21 2009

Status

approved