A248594 - OEIS

%I #11 Nov 02 2014 18:17:41

%S 153221,196621,222422,230261,288437,307373,340421,400082,657302,

%T 660713,706073,723461,777773,838562,843521,954581,961621,988601,

%U 1009985,1031846,1034933,1190822,1215821,1246802,1384621,1409873,1612321,1723082,1737122,1886441

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

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

%e a(1)=153221 because 153221 is a product of 2 primes (17*9013) and

%e 153222 is a product of 3 primes (2 * 3 * 25537) and

%e 153223 is a product of 4 primes (7 * 7 * 53 * 59) and

%e 153224 is a product of 5 primes (2 * 2 * 2 * 107 * 179) and

%e 153225 is a product of 6 primes (3 * 3 * 3 * 5 * 5 * 227).

%o (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

%Y Cf. A001358, A113150.

%K nonn,easy

%O 1,1

%A _Gil Broussard_, Oct 09 2014