Triangle, read by rows, of pairwise sums of trinomial coefficients (A027907).

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =5a(5) =1a(6) =4a(7) =13a(8) =9a(9) =1a(10) =5a(11) =26a(12) =35a(13) =14a(14) =1a(15) =6a(16) =45a(17) =96a(18) =75a(19) =20a(20) =1a(21) =7a(22) =71a(23) =216a(24) =267a(25) =140a(26) =27a(27) =1a(28) =8a(29) =105