Complete the series 11,15,19,18,26,21,32, 24,37,_ | with ANSWER

What will be the next number in this series? 

 11,15,19,18,26,21,32, 24,37,__

Answer:

27 is the answer.

Explanation
Even places are multiples of 3
Odd places have numbers with differences between them are decreasing arithmetic progression.

So,
Even places are 15,18,51,24,"27"
Odd places are 11,19,26,32,37,"41"