A124942 Numbers k such that k and k+5 are 5-almost primes.

675, 1323, 1372, 1480, 1750, 1875, 2295, 2920, 3100, 3856, 4095, 4120, 4180, 4275, 4375, 5175, 5427, 5643, 5775, 5980, 6370, 6375, 6520, 6723, 6820, 7150, 7155, 7203, 7240, 7245, 7960, 8325, 8883, 8920, 9075, 9207, 9555, 9620, 9625, 9747, 9855, 9940

Offset: 1

Author

Zak Seidov, Nov 13 2006

Keywords

• nonn
• changed

Examples

			675=3^3*5^2, 680=2^3*5*17; 1323=3^3*7^2, 1328=2^4*83.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A124940, A124941.

Programs

Mathematica

Select[Range[10000],PrimeOmega[#]==PrimeOmega[#+5]==5&] (* James C. McMahon, Dec 13 2024 *)
Select[Partition[Range[10000],6,1],PrimeOmega[#[[1]]]==PrimeOmega[#[[6]]]==5&][[;;,1]] (* Harvey P. Dale, Aug 27 2025 *)

PARI

isok(n) = (bigomega(n) == 5) && (bigomega(n+5) == 5); \\ Michel Marcus, Oct 11 2013