A046444 Composite numbers whose 4 prime factors are distinct in length.

2241998, 2250886, 2264218, 2268662, 2286394, 2290882, 2295326, 2295458, 2308658, 2309054, 2313586, 2330878, 2335322, 2336246, 2340778, 2354374, 2357542, 2361986, 2375186, 2375318, 2377034, 2381566, 2384602, 2398726

Offset

1,1

Comments

Equivalently, the products of 4 prime numbers that have distinct lengths when written in decimal. - Peter Munn, May 30 2023

Links

Table of n, a(n) for n=1..24.

Example

2241998 because 2241998 = 2 * 11 * 101 * 1009, which have 1, 2, 3, and 4 digits, respectively.

Mathematica

Select[Range[24*10^5], PrimeNu[#]==4&&Length[Union[IntegerLength/@ FactorInteger[ #][[All, 1]]]]==4&] (* Harvey P. Dale, Jan 12 2020 *)

Crossrefs

Subsequence of A046386.

Sequence in context: A224628 A224629 A224636 * A349722 A180940 A089445

Adjacent sequences: A046441 A046442 A046443 * A046445 A046446 A046447

Keyword

nonn,base

Author

Patrick De Geest, Jul 15 1998

Status

approved