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 A136356 #9 Aug 14 2025 00:56:30
%S A136356 4,6,9,15,30,105,420,1155,2310,15015,30030,255255,1021020,4849845,
%T A136356 19399380,111546435,669278610,9704539845,38818159380,100280245065,
%U A136356 601681470390,14841476269620,18551845337025,152125131763605
%N A136356 Increasing sequence obtained by union of two sequences A136353 and {b(n)}, where b(n) is the smallest composite number m such that m-1 is prime and the set of distinct prime factors of m consists of the first n primes.
%C A136356 This sequence is different from A070826 and A118750.
%e A136356 a(4)=15 because k=2 and prime factors are 3 and 5; 15 is odd and n-2=13, prime.
%t A136356 a[n_]:=(c=Product[Prime[k],{k,n}]; For[m=1,!(!PrimeQ[c*m]&&PrimeQ[c*m-1]&&Length[FactorInteger[c*m]]==n),m++ ]; c*m);
%t A136356 b[n_]:=(c=Product[Prime[k],{k,2,n+1}]; For[m=1,!(!PrimeQ[c(2m-1)]&&PrimeQ[c(2m-1)-2]&&Length[FactorInteger[c(2*m-1)]]==n),m++ ]; c(2m-1));
%t A136356 Take[Union[Table[a[k],{k,24}],Table[b[k],{k,24}]],24] (* _Farideh Firoozbakht_, Aug 13 2009 *)
%Y A136356 Cf. A136349-A136355, A136357-A136358, A070826, A118750.
%K A136356 easy,nonn
%O A136356 1,1
%A A136356 _Enoch Haga_, Dec 25 2007
%E A136356 Edited, corrected and extended by _Farideh Firoozbakht_, Aug 13 2009