A318959 Primes p (> 2) such that p - 2 and p - 1 are nonsquarefree.

29, 101, 127, 137, 149, 173, 277, 281, 317, 353, 389, 461, 509, 541, 569, 577, 641, 677, 727, 821, 857, 877, 929, 977, 1109, 1129, 1181, 1217, 1277, 1289, 1361, 1423, 1433, 1451, 1613, 1667, 1721, 1777, 1861, 1877, 1901, 1913, 1973, 2081, 2153, 2297, 2333, 2351

Offset

1,1

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Example

21 (= 23 - 2) is squarefree. So 23 is not a term.
27 = 3^3 and 28 = 2^2*7. So 29 is a term.

Mathematica

Select[Prime[Range[500]], !SquareFreeQ[# - 2] && !SquareFreeQ[# - 1] &] (* Vincenzo Librandi, Sep 06 2018 *)

Prog

(PARI) forprime(p=2, 1e4, if(!issquarefree(p-1)&&!issquarefree(p-2), print1(p, ", "))); \\ Altug Alkan, Sep 06 2018
(Magma) [p: p in PrimesInInterval(3, 2500)| not IsSquarefree(p-2) and not IsSquarefree(p-1)]; // Vincenzo Librandi, Sep 06 2018

Crossrefs

Cf. A000040, A039787, A049231, A240473, A257545, A319049.

Sequence in context: A087641 A161665 A127464 * A142109 A069472 A142138

Adjacent sequences: A318956 A318957 A318958 * A318960 A318961 A318962

Keyword

nonn

Author

Seiichi Manyama, Sep 06 2018

Status

approved