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 A268582 #19 Sep 14 2022 21:11:37 %S A268582 66,222,555,777,2222,3333,5555,7777,22222,33333,55555,77777,2222222, %T A268582 3333333,5555555,7777777,22222222222,33333333333,55555555555, %U A268582 77777777777,1111111111111,22222222222222222,33333333333333333,55555555555555555,77777777777777777,6666666666666666666 %N A268582 Sphenic numbers having identical digits. %C A268582 Subsequence of A007304 (sphenic numbers: products of 3 distinct primes). %C A268582 a(1)= A087331(4). %H A268582 Max Alekseyev, <a href="/A268582/b268582.txt">Table of n, a(n) for n = 1..89</a> %e A268582 222 is in the sequence because 222 = 2*3*37, product of 3 distinct primes. %p A268582 with(numtheory): %p A268582 for n from 1 to 23 do: %p A268582 for b from 1 to 9 do: %p A268582 x:=(((10^n)- 1)/9)*b:y:=factorset(x):n1:=nops(y): %p A268582 if bigomega(x)=3 and n1=3 %p A268582 then %p A268582 printf(`%d, `,x): %p A268582 else %p A268582 fi: %p A268582 od: %p A268582 od: %t A268582 Select[Flatten@ Map[Map[Function[k, FromDigits@ Table[k, {#}]], Range[1, 9]] &, Range@ 20], Length@ # == 3 && Times @@ Last /@ # == 1 &@ FactorInteger@ # &] (* _Michael De Vlieger_, Feb 07 2016 *) %Y A268582 Cf. A007304, A046053, A087331, A095370, A196104. %K A268582 nonn,base %O A268582 1,1 %A A268582 _Michel Lagneau_, Feb 07 2016