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 A282671 #16 Feb 25 2017 08:10:57 %S A282671 8,12,16,18,20,24,28,30,32,36,40,42,44,48,50,52,54,56,60,64,66,68,70, %T A282671 72,76,78,80,84,88,90,92,96,98,100,102,104,108,110,112,114,116,120, %U A282671 124,126,128,130,132,136,138,140,144,148,150,152,154,156,160,162,164,168,170,172,174 %N A282671 Twice composite numbers. %C A282671 Even numbers greater than 2 that do not appear in A001747. %F A282671 a(n) = 2*A002808(n). - _R. J. Mathar_, Feb 23 2017 %F A282671 a(n) = A139270(n+1). - _R. J. Mathar_, Feb 25 2017 %o A282671 (PARI) is(n)=n%2==0 && n>6 && !isprime(n/2) \\ _Charles R Greathouse IV_, Feb 21 2017 %Y A282671 Cf. A001747, A139270, A176100. %K A282671 nonn,easy %O A282671 1,1 %A A282671 _Alessandro Polcini_, Feb 20 2017