%I #12 Oct 27 2024 16:09:02

%S 210,46189,55913,62491,70499,75361,78793,81719,84227,89947,95381,

%T 96577,99671,100529,101959,103037,104533,110143,111397,114257,116831,

%U 121693,121771,124729,127699,128557,128843,130169,131461,133331,134849,139403,141427,143429

%N 4-brilliant numbers with distinct prime factors.

%H Michael S. Branicky, <a href="/A376864/b376864.txt">Table of n, a(n) for n = 1..10000</a>

%e 210 = 2*3*5*7 is a term.

%e 130169 = 13*17*19*31 is a term.

%o (Python)

%o from sympy import factorint

%o def ok(n):

%o f = factorint(n)

%o return len(f) == sum(f.values()) == 4 and len(set([len(str(p)) for p in f])) == 1

%o print([k for k in range(144000) if ok(k)]) # _Michael S. Branicky_, Oct 08 2024

%o (Python)

%o from math import prod

%o from sympy import primerange

%o from itertools import count, combinations, islice

%o def bgen(d): # generator of terms that are products of d-digit primes

%o primes, out = list(primerange(10**(d-1), 10**d)), set()

%o for t in combinations(primes, 4): out.add(prod(t))

%o yield from sorted(out)

%o def agen(): # generator of terms

%o for d in count(1): yield from bgen(d)

%o print(list(islice(agen(), 34))) # _Michael S. Branicky_, Oct 08 2024

%Y Intersection of A046386 and A376704.

%K nonn,base,easy

%O 1,1

%A _Paul Duckett_, Oct 07 2024

%E Terms corrected by _Michael S. Branicky_, Oct 08 2024