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 A262996 #14 Oct 26 2015 22:32:05
%S A262996 1223444433,1224343443,1233444243,1233444423,1234424343,1234442343,
%T A262996 1243344243,1243442433,1244332443,1244343423,1244344323,1244442333,
%U A262996 1323442443,1324244433,1324344423,1324443243,1324443423,1324444323,1332244443,1334244243,1334244423,1334424243,1342443243,1343242443
%N A262996 Ten-digit semiprimes with exactly one 1, two 2's, three 3's and four 4's.
%C A262996 From total 10!/(2!*3!*4!)=12600 ten-digit numbers with exactly one 1, two 2's, three 3's and four 4's, exactly 732 numbers are semiprimes of the form 3*prime.
%H A262996 Zak Seidov, <a href="/A262996/b262996.txt">Table of n, a(n) for n = 1..732</a>
%t A262996 Select[(FromDigits[#] & /@ Permutations[{1, 2, 2, 3, 3, 3, 4, 4, 4, 4}]), PrimeQ[#/3] &]
%o A262996 (PARI) forprime(p=407814811, 1481443741, d=digits(3*p); if(vecsort(d)==[1, 2, 2, 3, 3, 3, 4, 4, 4, 4], print1(3*p", "))) \\ _Charles R Greathouse IV_, Sep 24 2015
%Y A262996 Cf. A022915.
%K A262996 nonn,base,fini,full
%O A262996 1,1
%A A262996 _Zak Seidov_, Oct 07 2015