A358988 Oblong numbers which are products of four distinct primes.

210, 462, 870, 930, 1122, 1190, 1482, 1722, 1806, 3306, 4422, 4970, 6162, 7310, 7482, 8742, 8930, 10302, 10506, 11990, 12882, 14042, 15006, 17030, 17822, 18906, 19182, 20022, 20306, 21170, 25122, 30102, 31506, 32942, 36290, 40602, 41006, 42230, 45582, 46010, 47306

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

210 = 14*15 = 2*3*5*7.
1122 = 33*34 = 2*3*11*17.
10302 = 101*102 = 2*3*17*101.
20306 = 142*143 = 2*11*13*71.

Mathematica

Select[(#*(# + 1)) & /@ Range[220], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1} &] (* Amiram Eldar, Dec 10 2022 *)
Select[Times@@@Partition[Range[400], 2, 1], PrimeNu[#]==PrimeOmega[#]==4&] (* Harvey P. Dale, Jul 08 2025 *)

Crossrefs

Intersection of A002378 and A046386.

Sequence in context: A360146 A147571 A306508 * A254466 A235304 A121479

Adjacent sequences: A358985 A358986 A358987 * A358989 A358990 A358991

Keyword

nonn

Author

Massimo Kofler, Dec 10 2022

Status

approved