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 A218558 #12 Aug 30 2017 03:01:37 %S A218558 8,12,27,42,42,52,63,75,92,92,102,114,124,138,147,153,164,171,182,195, %T A218558 207,212,222,231,242,255,261,273,282,292,310,316,322,332,343,354,363, %U A218558 374,385,399,402,412,423,434,442,452,465,474,483,494,506 %N A218558 Next number that is the product of exactly three (not necessarily distinct) primes, after 10*n. %C A218558 This is to "triprimes" A014612 as A185008 is to semiprimes A001358, and as A218255 is to primes A000040. %C A218558 The first equal terms are a(4) = a(5) = 42. The density of numbers n such that a(n) = a(n+1) is 1. Similarly, the density of numbers n such that a(n) = a(n+1) = ... = a(n+k) is 1 for any fixed k. - _Charles R Greathouse IV_, Aug 30 2017 %F A218558 a(n) = MIN[k in A014612 and k > 10*n = A008592(n)]. %e A218558 a(0) = 8, the first number that is the product of exactly three (not necessarily distinct) primes. %e A218558 a(1) = 12 = 2^2 * 3, which is >10*1=10. %e A218558 a(3) = 42 even though 30 = 2*3*5 is a "triprime" because we use ">" rather that ">=" in the definition. %o A218558 (PARI) a(n)=n*=10; while(bigomega(n++)!=3, ); n \\ _Charles R Greathouse IV_, Aug 30 2017 %Y A218558 Cf. A008592, A014612, A218255, A185008. %K A218558 nonn,easy %O A218558 1,1 %A A218558 _Jonathan Vos Post_, Nov 02 2012 %E A218558 Offset corrected by _Charles R Greathouse IV_, Aug 30 2017