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 A175587 #9 Jan 25 2017 01:37:08 %S A175587 4,6,9,14,21,26,33,35,38,49,51,58,65,82,85,87,94,111,118,121,123,134, %T A175587 141,143,145,158,161,166,169,206,209,214,217,219,221,226,237,254,259, %U A175587 262,265,267,274,287,289,291,298,301,303,305,334,339,341,346,365,382 %N A175587 a(1) = 4; a(n) = smallest semiprime such that a(n) - a(n-1) is prime. %C A175587 First differences: 2, 3, 5, 7, 5, 7, 2, 3, 11, 2, 7, 7, 17, 3, 2, 7, 17, 7, 3, 2, 11, 7, 2, 2, 13, 3, 5, 3, 37, 3, 5, 3, 2, 2, 5, 11, 17, 5, 3, 3, 2, 7, 13, 2, 2, 7, 3, 2, 2 (all primes). %H A175587 Zak Seidov, <a href="/A175587/b175587.txt">Table of n, a(n) for n = 1..1000</a> %t A175587 NestList[(p = 2; While[2 != PrimeOmega[q = # + p], p = NextPrime[p]]; q) &, 4, 50] %o A175587 (PARI) nxt(n)=forprime(p=2,, if(bigomega(n+p)==2, return(n+p))) \\ _Charles R Greathouse IV_, Jan 25 2017 %Y A175587 Cf. A001358 (semiprimes). %K A175587 nonn %O A175587 1,1 %A A175587 _Zak Seidov_, Jul 17 2010