A248594 Semiprimes whose next four consecutive integers have exactly three, four, five, and six prime factors, respectively (allowing multiplicity of factors).

153221, 196621, 222422, 230261, 288437, 307373, 340421, 400082, 657302, 660713, 706073, 723461, 777773, 838562, 843521, 954581, 961621, 988601, 1009985, 1031846, 1034933, 1190822, 1215821, 1246802, 1384621, 1409873, 1612321, 1723082, 1737122, 1886441

Offset: 1

Author

Gil Broussard, Oct 09 2014

Keywords

• nonn
• easy

Comments

This sequence is related to A113150; for instance, a(14) = 838562 = A113150(1) + 1, since 838561 is prime. - Michel Marcus, Oct 23 2014

Examples

			a(1)=153221 because 153221 is a product of 2 primes (17*9013) and
153222 is a product of 3 primes (2 * 3 * 25537) and
153223 is a product of 4 primes (7 * 7 * 53 * 59) and
153224 is a product of 5 primes (2 * 2 * 2 * 107 * 179) and
153225 is a product of 6 primes (3 * 3 * 3 * 5 * 5 * 227).
		

Crossrefs

Cf. A001358, A113150.

Programs

PARI

isok(n) = bigomega(n)==2 && bigomega(n+1)==3 && bigomega(n+2)==4 && bigomega(n+3)==5 && bigomega(n+4)==6; \\ Michel Marcus, Oct 23 2014