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 A115402 #5 Nov 09 2012 08:48:53 %S A115402 12,15,10,10,15,16,15,8,8,18,16,16,7,9,8,8,17,22,21,10,7,11,12,11,7, %T A115402 10,9,13,14,22,18,15,7,16,12,16,7,7,4,4,10,12,13,8,9,19,22,27,23,19, %U A115402 14,8,11,8 %N A115402 Difference between 3-almostprime(n) and 3-almostprime(n+3). %H A115402 Harvey P. Dale, <a href="/A115402/b115402.txt">Table of n, a(n) for n = 1..1000</a> %F A115402 a(n) = A014612(n+3) - A014612(n). %e A115402 a(1) = A014612(1+3) - A014612(1) = 20 - 8 = 12. %e A115402 a(2) = A014612(2+3) - A014612(2) = 27 - 12 = 15. %e A115402 a(3) = A014612(3+3) - A014612(3) = 28 - 18 = 10. %e A115402 a(39) = A014612(39+3) - A014612(39) = 174 - 170 = 4. %t A115402 Last[#]-First[#]&/@Partition[Select[Range[300],PrimeOmega[#]==3&],4,1] (* _Harvey P. Dale_, Nov 09 2012 *) %Y A115402 Cf. A014612, A056809, A067813, A113789, A115403. %K A115402 easy,nonn %O A115402 1,1 %A A115402 _Jonathan Vos Post_, Jan 22 2006