This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A359645 #18 Jun 27 2025 17:28:17
%S A359645 0,0,0,0,20,1235,32396,605939,9446284,131733664,1706815354,
%T A359645 21008871506,249145286508,2873325692759,32433194803107,
%U A359645 359960491516138,3941261642520039,42679704453671033,457980431402674541
%N A359645 Number of numbers <= 10^n that are products of 6 distinct primes.
%e A359645 a(5) = 20 = #{30030, 39270, 43890, 46410, 51870, 53130, 62790, 66990, 67830, 71610, 72930, 79170, 81510, 82110, 84630, 85470, 91770, 94710, 98670, 99330}.
%o A359645 (PARI) a(n) = my(N=10^n); (f(m, p, k, j=1)=my(s=sqrtnint(N\m, k), count=0); if(k==2, forprime(q=p, s, count += primepi(N\(m*q)) - j; j+=1); return(count)); forprime(q=p, s, count += f(m*q, q+1, k-1, j+1); j+=1); count); f(1, 2, 6); \\ _Daniel Suteu_, Jan 11 2023
%Y A359645 Cf. A006880, A036351, A067885, A215218, A359642, A359644.
%K A359645 nonn,more
%O A359645 1,5
%A A359645 _Peter Dolland_, Jan 09 2023
%E A359645 a(13)-a(14) from _Daniel Suteu_, Jan 11 2023
%E A359645 a(15)-a(19) from _Henri Lifchitz_, Feb 01 2025