Find Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

'2'

This single sequence in fact consists of two sequences: the first sequence is 2-3-4-5-... and the second sequence is 9-18-36-72-... . To make the puzzle harder, all digits have been placed apart. Conclusion: the next term in the sequence is a '2'.