Left border of triangle A137629.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =11a(5) =18a(6) =26a(7) =39a(8) =55a(9) =79a(10) =106a(11) =150a(12) =196a(13) =267a(14) =349a(15) =464a(16) =592a(17) =781a(18) =984a(19) =1275a(20) =1601a(21) =2041a(22) =2536a(23) =3217a(24) =3961a(25) =4961a(26) =6094a(27) =7566a(28) =9220a(29) =11392