Van der Waerden numbers W(2;2,n-1).

Terms

a(0) =2a(1) =6a(2) =9a(3) =18a(4) =22a(5) =32a(6) =46a(7) =58a(8) =77a(9) =97a(10) =114a(11) =135a(12) =160a(13) =186a(14) =218