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 A136196 #12 Oct 15 2021 14:45:16 %S A136196 4,49,55,91,119,143,159,183,185,203,215,219,235,247,265,287,289,299, %T A136196 303,319,321,327,339,391,411,413,415,451,469,471,515,517,527,533,535, %U A136196 543,551,579,581,589,667,669,679,685,687,695,721,753,779,789,791,813,815 %N A136196 Numbers n such that n and n+2 are consecutive semiprimes. %H A136196 Zak Seidov, <a href="/A136196/b136196.txt">Table of n, a(n) for n = 1..1000.</a> %e A136196 4 and 6 are 1st and 2nd semiprimes, %e A136196 49 and 51 are 17th and 18th semiprimes, %e A136196 55 and 57 are 19th and 20th semiprimes. %t A136196 Position[Partition[PrimeOmega[Range[900]],3,1],_?(#[[1]]==#[[3]]==2 && #[[2]]!=2&),1,Heads->False]//Flatten (* _Harvey P. Dale_, Oct 15 2021 *) %o A136196 (PARI) isok(n) = (bigomega(n) == 2) && (bigomega(n+2) == 2) && (bigomega(n+1) != 2); \\ _Michel Marcus_, Oct 13 2013 %Y A136196 Cf. A001358, A065516. %K A136196 nonn %O A136196 1,1 %A A136196 _Zak Seidov_, Dec 21 2007