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 A242868 #7 Jul 30 2015 18:11:09 %S A242868 3,14,15,16,17,18,22,24,25,27,28,40,41,42,50,51,52,60,61,70,71,72,80, %T A242868 81,82,102,104,105,107,108,112,114,115,117,118,120,121,123,125,126, %U A242868 128,132,140,141,144,145,146,147,148,150,151,152,154,156,157,158,162,164 %N A242868 Numbers n such that sum of the factorial of digits of n is semiprime. %H A242868 K. D. Bajpai, <a href="/A242868/b242868.txt">Table of n, a(n) for n = 1..10000</a> %e A242868 a(4) = 16: 1! + 6! = 1 + 720 = 721 = 7 * 103 which is semiprime. %e A242868 a(9) = 25: 2! + 5! = 2 + 120 = 122 = 2 * 61 which is semiprime. %p A242868 with(numtheory):A242868:= proc() local a; a:=add( i!,i = convert((n), base, 10))(n);if bigomega(a)=2 then RETURN (n);fi; end: seq(A242868 (), n=1..300); %t A242868 Select[Range[200],PrimeOmega[Total[IntegerDigits[#]!]]==2&] (* _Harvey P. Dale_, Jul 30 2015 *) %Y A242868 Cf. A001358, A061602, A165451. %K A242868 nonn,base %O A242868 1,1 %A A242868 _K. D. Bajpai_, May 24 2014