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 A199992 #13 Apr 10 2015 14:14:27 %S A199992 25,26,27,28,34,35,36,38,44,45,46,48,52,54,56,58,62,63,64,65,72,76,82, %T A199992 84,85,92,99,125,126,128,129,134,135,136,138,143,144,145,146,148,152, %U A199992 153,154,156,158,162,164,165,172,176,182,183,184,185,192,215,216 %N A199992 Composite numbers whose multiplicative persistence is 2. %C A199992 Complement of A046502 with respect to A046511. %H A199992 Harvey P. Dale, <a href="/A199992/b199992.txt">Table of n, a(n) for n = 1..1000</a> %e A199992 125 -> 1 * 2 * 5-> [ 10 ] -> 1 * 0 -> [ 0 ] -> one digit in two steps. %t A199992 persistence[n_] := Module[{cnt = 0, k = n}, While[k > 9, cnt++; k = Times @@ IntegerDigits[k]]; cnt]; Select[Range[400], ! PrimeQ[#] && persistence[#] == 2 &] (* _T. D. Noe_, Nov 23 2011 *) %t A199992 Select[Range[250],CompositeQ[#]&&Length[NestWhileList[Times@@ IntegerDigits[ #]&,#,#>9&]] == 3&] (* _Harvey P. Dale_, Apr 10 2015 *) %Y A199992 Cf. A046502 (primes whose multiplicative persistence is 2). %K A199992 nonn,base %O A199992 1,1 %A A199992 _Jaroslav Krizek_, Nov 13 2011