A308735 Numbers k such that k, k+2, k+4 are of the form p^2*q where p and q are distinct primes.

2523, 2525, 3175, 22021, 25529, 28223, 40325, 53573, 58923, 73447, 122571, 132021, 149675, 152339, 165175, 172917, 202221, 209673, 235825, 267773, 268223, 308671, 322223, 371075, 425723, 430171, 445923, 488975, 575973, 591575

Offset

1,1

Comments

All terms are odd. See comment in A308736. - Chai Wah Wu, Jun 24 2019

Links

Ray Chandler, Table of n, a(n) for n = 1..10000

Example

3175 =  5 *  5 * 127,
3177 =  3 *  3 * 353,
3179 = 11 * 17 *  17.

Mathematica

psx = Table[{0}, {5}]; nmax = 600000; n = 1; lst = {};
While[n < nmax, n++;
  psx = RotateRight[psx];
  psx[[1]] = Sort[Last /@ FactorInteger[n]];
  If[Union[{psx[[1]], psx[[3]], psx[[5]]}] == {{1, 2}},
   AppendTo[lst, n - 4]]; ];
lst

Crossrefs

Cf. A074173, A308736.

Sequence in context: A264339 A045942 A375239 * A096026 A278003 A308736

Adjacent sequences: A308732 A308733 A308734 * A308736 A308737 A308738

Keyword

nonn

Author

Ray Chandler, Jun 24 2019

Status

approved