|
%I #30 Feb 08 2015 07:15:15
%S 4,6,15,26,55,111,237,469,926,1858,3711,7419,14849,29693,59435,118821,
%T 237722,475378,950738,1901474,3802967,7605921,15211942,30423869,
%U 60847667,121695326,243390743,486781401,973562795,1947125641,3894251303,7788502531,15577005118
%N Sequence of semiprimes with all cumulating sums being semiprime.
%C a(1)=4, then a(n) is the least semiprime > a(n-1) such that a(1)+...+a(n) is semiprime.
%H Zak Seidov, <a href="/A254325/b254325.txt">Table of n, a(n) for n = 1..89</a>
%e 4+6=10=2*5, 10+15=25=5*5, 25+26=51=3*17.
%t s={4};a=4;Do[m=a+1;While[2!=PrimeOmega[m]||2!=PrimeOmega[m+a],m++]; AppendTo[s,m];a=m+a,{50}];s
%o (PARI){s=[4];a=4;
%o for(k=1,50,m=a+1while(2<>bigomega(m)||2<>bigomega(m+a),m++);
%o s=concat(s, m);a=m+a);s}
%Y Cf. A001358 (semiprimes), A065516.
%K nonn
%O 1,1
%A _Zak Seidov_, Feb 05 2015
|
