A346297 - OEIS

%I #18 Oct 02 2021 23:01:13

%S 4,6,15,21,39,49,51,62,74,77,87,94,95,111,129,133,142,158,166,178,183,

%T 185,187,203,205,209,214,218,226,237,287,298,302,309,323,326,334,346,

%U 355,361,362,365,371,382,394,398,451,473,478,489,497,519,529,554,562,591,597,623,649,662,669,679,689,697,707,717,746

%N Slowest growing sequence of semiprimes such that any accumulating sum is a semiprime.

%H Charles R Greathouse IV, <a href="/A346297/b346297.txt">Table of n, a(n) for n = 1..10000</a>

%e 4 + 6 = 10 = 2*5, 10 + 15 = 25 = 5*5, 25 + 21 = 46 = 2*23.

%t s = {4}; t = 4; Do[While[2 != PrimeOmega[n] || 2 != PrimeOmega[t + n] , n++]; AppendTo[s, n]; t = t + n; n++, {50}]; s

%o (PARI) issemi(n)=bigomega(n)==2;

%o first(n)=my(v=vector(n),s,t); s=v[1]=4; for(k=2,n, t=v[k-1]; while(!issemi(t++) || !issemi(s+t), ); s+=v[k]=t); v; \\ _Charles R Greathouse IV_, Oct 02 2021

%Y Cf. A001222, A001358, A116656.

%K nonn

%O 1,1

%A _Zak Seidov_, Sep 28 2021