Pairs of numbers of the form 2^i * 3^j such that there are no primes between them.
3, 4, 8, 9, 24, 27, 32, 36
1
This sequence seems complete.
T. D. Noe, Plot of 8 terms
Vic Bold, Puzzle 805: Prime gaps containing...
(Mma) nn = 30; t = Table[2^a 3^b, {a, 0, nn}, {b, 0, nn*Log[3, nn]/Log[2, nn]}]; t = Union[Select[Flatten[t], # <= 2^nn &]]; Select[Partition[t, 2, 1], PrimePi[#[[1]]] == PrimePi[#[[2]]] &]
nonn
T. D. Noe, Oct 28 2015