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 A245382 #15 Jul 21 2014 18:26:41 %S A245382 19,23,37,41,53,61,73,127,137,157,173,191,251,271,313,317,331,521,571, %T A245382 751,911,1123,1153,1213,1217,1231,1321,1531,1571,1721,2113,2131,2311, %U A245382 2711,3121,3511,4111,5113,5171,5711,7121,7151,7211,11119,11161,11173,11177,11213 %N A245382 Primes whose product of digits is a semiprime. %C A245382 The linked table includes probable primes. - _Jens Kruse Andersen_, Jul 21 2014 %H A245382 K. D. Bajpai and Jens Kruse Andersen, <a href="/A245382/b245382.txt">Table of n, a(n) for n = 1..10000</a> (first 370 terms from K. D. Bajpai) %e A245382 137 is prime. 1 * 3 * 7 = 21 = 3 * 7, which is semiprime. %e A245382 251 is prime. 2 * 5 * 1 = 10 = 2 * 5, which is semiprime. %t A245382 Select[Prime[Range[1000]], PrimeOmega[(Times @@ IntegerDigits[#])] == 2 &] %o A245382 (PARI) f(n,b,d) = if(d, for(i=1, 9, if(b+bigomega(i)<=2, f(10*n+i, b+bigomega(i), d-1))), if(b==2 && isprime(n), print1(n", "))) %o A245382 for(d=1, 8, f(0,0,d)) \\ f(0,0,d) prints d-digit terms. _Jens Kruse Andersen_, Jul 21 2014 %Y A245382 Cf. A000040, A001358, A046703, A007954. %K A245382 nonn,base %O A245382 1,1 %A A245382 _K. D. Bajpai_, Jul 20 2014