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A248594 Semiprimes whose next four consecutive integers have exactly three, four, five, and six prime factors, respectively (allowing multiplicity of factors). 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

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).

PROG

(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

CROSSREFS

Cf. A001358, A113150.

Sequence in context: A233947 A172732 A172789 * A339528 A234553 A073086

Adjacent sequences: A248591 A248592 A248593 * A248595 A248596 A248597

KEYWORD

nonn,easy

AUTHOR

Gil Broussard, Oct 09 2014

STATUS

approved

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Last modified November 27 21:40 EST 2022. Contains 358406 sequences. (Running on oeis4.)