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 A235690 #10 Apr 29 2014 22:49:29 %S A235690 10,14,15,21,25,26,34,35,38,39,46,49,51,57,58,62,65,69,74,82,85,86,87, %T A235690 91,93,94,95,115,118,119,121,122,133,141,155,161,166,177,202,221,226, %U A235690 262,299,303,323,334,335,339,355,377,393,411,422,445,446,447,454 %N A235690 Semiprimes which have one or more occurrences of exactly two different digits. %C A235690 The first term having a repeated digit is 115. %e A235690 1000000000010101 is a term because it is made of the digits 0 and 1 and it is the product of the two primes 18463559 and 54160739. %t A235690 Select[Range[454], Length@Union@ IntegerDigits[#] == 2 && Total[Last /@ FactorInteger[#]] == 2 &] (* _Giovanni Resta_, Jan 14 2014 *) %o A235690 (PARI) %o A235690 list(lim)=my(v=List(), t); forprime(p=2, sqrt(lim), t=p; forprime(q=p, lim\t, listput(v, t*q))); vecsort(Vec(v)) \\ From A001358 %o A235690 b=list(10000); s=[]; for(n=1, #b, if(#vecsort(eval(Vec(Str(b[n]))),,8)==2, s=concat(s, b[n]))); s %Y A235690 Cf. A235691-A235696. %Y A235690 Cf. A235154-A235161. %K A235690 nonn,base %O A235690 1,1 %A A235690 _Colin Barker_, Jan 14 2014