A321505 - OEIS

A321505

Numbers k such that k and k+1 each have at least 5 distinct prime factors.

254540, 310155, 378014, 421134, 432795, 483405, 486590, 486794, 488565, 489345, 507129, 522444, 545258, 549185, 558789, 558830, 567644, 577940, 584154, 591260, 598689, 627095, 634809, 637329, 663585, 666995, 667029, 678755, 687939, 690234, 707420, 712425, 720005, 720290, 728364, 743589

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OFFSET

1,1

COMMENTS

Equals A140079 up to a(34) but a(35) = 728364 is not in A140079, see A321495.

LINKS

M. F. Hasler, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[750000], PrimeNu[#] > 4 && PrimeNu[# + 1] > 4 &] (* Amiram Eldar, Nov 12 2018 *)

PROG

(PARI) is(n)=omega(n)>=5&&omega(n+1)>=5

CROSSREFS

Cf. A140079 (variant with "exactly 5"), A321495 (terms not in A140079).

Cf. A321504 (analog for k=4 prime factors), A321506 (analog for k=6).

Sequence in context: A069176 A253725 A140079 * A034631 A168352 A147579

Adjacent sequences: A321502 A321503 A321504 * A321506 A321507 A321508

KEYWORD

nonn

AUTHOR

M. F. Hasler, Nov 12 2018

STATUS

approved