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 A199983 #15 Aug 03 2014 14:01:36
%S A199983 41,89,127,139,193,271,277,379,383,397,463,643,677,727,739,937,1193,
%T A199983 1217,1249,1277,1319,1429,1721,1913,1931,1973,2377,2711,3119,3191,
%U A199983 3313,3331,3373,3461,3719,3727,3733,3911,3917,4111,4129,4219,6143,7121,7127,7193
%N A199983 Primes whose multiplicative digital root is 4.
%C A199983 Complement of A199984 with respect to A034051.
%C A199983 Can this sequence be proved to be infinite? [_Charles R Greathouse IV_, Nov 13 2011]
%e A199983 Prime 139 is in sequence because 1*3*9=27, 2*7=14, 1*4=4.
%t A199983 t = {}; n = 0; While[Length[t] < 100, n = NextPrime[n]; s = n; While[s >= 10, s = Times @@ IntegerDigits[s]]; If[s == 4, AppendTo[t, n]]]; t (* _T. D. Noe_, Nov 16 2011 *)
%Y A199983 Cf. A199984 (composite numbers whose multiplicative digital root is 4).
%Y A199983 Cf. A034051 (numbers whose multiplicative digital root is 4).
%K A199983 nonn,base
%O A199983 1,1
%A A199983 _Jaroslav Krizek_, Nov 13 2011