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 A118724 #4 Oct 31 2013 12:17:39 %S A118724 2,3,5,7,13,17,31,37,53,71,113,131,137,157,211,311,317,359,389,431, %T A118724 557,571,751,827,839,953,983,1117,1151,1297,1367,1511,1553,1621,1637, %U A118724 1759,2111,2179,2213,2269,2339,2393,2699,2719,2969,2971,3167,3221,3329,3511 %N A118724 Chen primes for which the multiplicative digital root is also a Chen prime. %e A118724 157 is in the sequence because (1) it is a Chen prime and (2) the multiplicative digital root 5 is also a Chen prime. %t A118724 mdr[n_] := NestWhile[Times @@ IntegerDigits@# &, n, # > 9 &]; chenQ[n_] := PrimeQ[n] && Plus @@ Last /@ FactorInteger[n + 2] < 3; Select[ Prime@ Range@500, chenQ@ mdr@# && chenQ@# &] (* _Robert G. Wilson v_ *) %Y A118724 Cf. A109611. %K A118724 base,nonn %O A118724 1,1 %A A118724 Luc Stevens (lms022(AT)yahoo.com), May 21 2006 %E A118724 More terms from _Robert G. Wilson v_, May 22 2006