OFFSET
1,1
COMMENTS
The smallest candidate for the next term in the b-file is A000931(1958), which is composite with 239 digits and an unknown number of prime factors. - Hugo Pfoertner, Sep 07 2017
LINKS
Hugo Pfoertner, Table of n, a(n) for n = 1..54
Eric Weisstein's World of Mathematics, Semiprime
MAPLE
select(x-> numtheory[bigomega](x)=2, [(<<0|1|0>,
<0|0|1>, <1|1|0>>^i)[1$2]$i=0..300])[]; # Alois P. Heinz, Aug 31 2017
MATHEMATICA
SemiprimeQ[1] := False SemiprimeQ[n_Integer] := Plus @@ (Last /@ FactorInteger[n]) == 2 a = Table[ SeriesCoefficient[ Series[x/(1 - x^2 - x^3), {x, 0, 50}], n], {n, 0, 50}] f[n_] = If[SemiprimeQ[a[[n]]] == True, a[[n]], {}] Flatten[Table[f[n], {n, 1, Length[a]}]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Sep 15 2006
EXTENSIONS
More terms from Alois P. Heinz, Aug 31 2017
STATUS
approved