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 A283597 #24 Dec 23 2024 21:57:35 %S A283597 8,14,19,41,42,43,48,49,59,74,84,85,88,92,93,97,108,113,116,132,139, %T A283597 144,148,149,157,158,159,162,163,189,190,193,198,209,210,211,222,223, %U A283597 224,225,226,227,231,234,235,250,251,259,264,272,280,285,306,307,315,316,317,318,319,320,323,326,327,340,345,349,358,361,368,376,386,387,388 %N A283597 Numbers n such that both 6n+1 and 6n+7 are semiprimes. %C A283597 Both n and n+1 are terms in A112775. %H A283597 Robert Israel, <a href="/A283597/b283597.txt">Table of n, a(n) for n = 1..10000</a> %p A283597 filter:= n -> numtheory:-bigomega(6*n+1) = 2 and numtheory:-bigomega(6*n+7) = 2: %p A283597 select(filter, [$1..1000]); # _Robert Israel_, Dec 23 2024 %t A283597 po[x_]=PrimeOmega[x]; Select[Range[500], po[6# + 1] == po[6# + 7] == 2 &] %o A283597 (PARI) for(n=1, 388, if(bigomega(6*n + 1) == 2 && bigomega(6*n + 7) == 2, print1(n,", "))) \\ _Indranil Ghosh_, Mar 15 2017 %Y A283597 Cf. A112771 (6n+1 semiprimes), A112775 (6n+1 is semiprime), A001358 (semiprimes). %K A283597 nonn %O A283597 1,1 %A A283597 _Zak Seidov_, Mar 14 2017