A061368 Lesser of twin primes (p, p+2) whose average p+1 is not squarefree.

3, 11, 17, 59, 71, 107, 149, 179, 191, 197, 227, 239, 269, 311, 347, 419, 431, 521, 599, 659, 809, 827, 881, 1019, 1031, 1049, 1061, 1091, 1151, 1277, 1319, 1427, 1451, 1487, 1607, 1619, 1667, 1787, 1871, 1931, 1949, 1997, 2027, 2087, 2111, 2141, 2267

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)

Formula

Intersection of A014574 and A013929.

Mathematica

Select[Select[Partition[Prime[Range[400]], 2, 1], #[[2]]-#[[1]]==2&][[All, 1]], !SquareFreeQ[#+1]&] (* Harvey P. Dale, Oct 21 2016 *)

Prog

(PARI) { n=-1; forprime (p=2, 119099, if (isprime(p+2) && !issquarefree(p+1), write("b061368.txt", n++, " ", p)) ) } \\ Harry J. Smith, Jul 22 2009
(Magma) [p:p in PrimesUpTo(2500)| IsPrime(p+2) and not IsSquarefree(p+1)]; // Marius A. Burtea, Jan 16 2020

Crossrefs

Cf. A001359, A005117, A014574, A013929.

Sequence in context: A245045 A127996 A032008 * A145701 A072982 A124787

Adjacent sequences: A061365 A061366 A061367 * A061369 A061370 A061371

Keyword

nonn

Author

Labos Elemer, Jun 07 2001

Extensions

Offset corrected by Amiram Eldar, Jan 16 2020

Status

approved