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A046444 Composite numbers whose 4 prime factors are distinct in length. 1

%I #21 May 30 2023 07:43:48

%S 2241998,2250886,2264218,2268662,2286394,2290882,2295326,2295458,

%T 2308658,2309054,2313586,2330878,2335322,2336246,2340778,2354374,

%U 2357542,2361986,2375186,2375318,2377034,2381566,2384602,2398726

%N Composite numbers whose 4 prime factors are distinct in length.

%C Equivalently, the products of 4 prime numbers that have distinct lengths when written in decimal. - _Peter Munn_, May 30 2023

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

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

%Y Subsequence of A046386.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jul 15 1998

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Last modified June 20 11:12 EDT 2024. Contains 373527 sequences. (Running on oeis4.)