A319050 Primes p such that neither p + 1 nor p + 2 is squarefree.

7, 23, 43, 47, 79, 97, 151, 167, 223, 241, 331, 349, 359, 367, 439, 523, 547, 619, 691, 727, 773, 823, 839, 907, 1051, 1087, 1123, 1223, 1231, 1249, 1303, 1367, 1423, 1447, 1483, 1523, 1571, 1627, 1663, 1699, 1723, 1811, 1823, 1847, 1861, 1879, 1951, 1987, 2131, 2203, 2207

Offset

1,1

Links

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

Example

8 = 2^3 and 9 = 3^2. So 7 is a term.
24 = 2^3*3 and 25 = 5^2. So 23 is a term.

Mathematica

Select[Prime[Range[400]], NoneTrue[#+{1, 2}, SquareFreeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 05 2019 *)

Prog

(PARI) isok(p) = isprime(p) && !issquarefree(p+1) && !issquarefree(p+2); \\ Michel Marcus, Sep 09 2018

Crossrefs

Cf. A000040, A049098, A257108, A318959, A319051.

Sequence in context: A213632 A031095 A375352 * A031371 A176557 A370643

Adjacent sequences: A319047 A319048 A319049 * A319051 A319052 A319053

Keyword

nonn

Author

Seiichi Manyama, Sep 08 2018

Status

approved