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

Author

Ray Chandler, Jun 24 2019

Keywords

• nonn

Comments

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

Examples

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

Links

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

Crossrefs

Cf. A074173, A308736.

Programs

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