OFFSET
1,1
COMMENTS
Runs of semiprimes of the same parity: {4, 6}, {9}, {10, 14}, {15, 21}, {22}, {25}, {26}, {33}, {34}, {35}, {38}, {39}, {46}, {49, 51, 55, 57}, {58, 62}, {65, 69}, {74}, {77}, {82}, {85}, {86}, {87, 91, 93}, {94}, ...
a(12) > 2*10^14.
EXAMPLE
a(1) = 22 since it is the first occurrence of a single even semiprime;
a(2) = 4 since 4 is the first of two consecutive even semiprimes in the sequence of semiprimes;
a(3) = 454 since it is the first of three consecutive even semiprimes in the sequence of semiprimes; etc.
MATHEMATICA
SplitBy[ Select[ Range@ 100, PrimeOmega@# == 2 &], Mod[#, 2] &] (* to view the runs of semiprimes of the same parity *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
STATUS
approved