A319049 -id:A319049 - cp's OEIS frontend

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

Seiichi Manyama, Sep 06 2018

nonn

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

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

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

[p: p in PrimesInInterval(3, 2500)| not IsSquarefree(p-2) and not IsSquarefree(p-1)]; // Vincenzo Librandi, Sep 06 2018

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

forprime(p=2, 1e4, if(!issquarefree(p-1)&&!issquarefree(p-2), print1(p, ", "))); \\ Altug Alkan, Sep 06 2018

A319051 Primes p such that none of p + 1, p + 2 and p + 3 are squarefree.

Original entry on oeis.org

47, 97, 241, 349, 547, 773, 1249, 1447, 1663, 1847, 1861, 2347, 2887, 3049, 3547, 3607, 3623, 3697, 4111, 4373, 4597, 5237, 5273, 5749, 6173, 6857, 7549, 8467, 8647, 8719, 9161, 9349, 9547, 9749, 11149, 11321, 11447, 12049, 12473, 12689, 12823, 12941, 13147, 13291

Offset: 1

Seiichi Manyama, Sep 08 2018

nonn

			48 = 2^4*3, 49 = 7^2 and 50 = 2*5^2. So 47 is a term.
98 = 2*7^2, 99 = 3^2*11 and 100 = 2^2*5^2. So 97 is a term.

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

Cf. A000040, A049098, A257108, A319049, A319050.

forprime(p=2, 1e5, if(!issquarefree(p+1) && !issquarefree(p+2) && !issquarefree(p+3), print1(p", ")))

cp's OEIS Frontend

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

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