A366217 - OEIS

%I #9 Oct 09 2023 12:10:25

%S 4,6,14,21,38,62,106,169,278,451,731,1186,1919,3106,5027,8135,13165,

%T 21302,34473,55779,90253,146035,236291,382327,618622,1000951,1619581,

%U 2620538,4240121,6860662,11100785,17961455,29062241,47023697,76085941,123109639,199195583,322305254,521500838,843806099

%N a(n) is the least semiprime > a(n-2) + a(n-1), with a(1) = 4 and a(2) = 6.

%H Robert Israel, <a href="/A366217/b366217.txt">Table of n, a(n) for n = 1..300</a>

%e a(3) = 14 because 14 = 2*7 is a semiprime, 14 > a(1) + a(2) = 10, and none of 11, 12 and 13 are semiprimes.

%p R:= 4,6: a:= 4: b:= 6:

%p for count from 3 to 100 do

%p   for v from a+b+1 do

%p     if numtheory:-bigomega(v) = 2 then

%p        R:= R,v; a:= b; b:= v; break

%p     fi

%p od od:

%p R;

%Y Cf. A001358.

%K nonn

%O 1,1

%A _Zak Seidov_ and _Robert Israel_, Oct 04 2023