Number of matching pairs of patterns, the first of length n and the second of length k.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =3a(5) =3a(6) =13a(7) =13a(8) =25a(9) =13a(10) =75a(11) =75a(12) =185a(13) =213a(14) =75a(15) =541a(16) =541a(17) =1471a(18) =2719a(19) =2053a(20) =541a(21) =4683a(22) =4683a(23) =13265a(24) =32973a(25) =40367a(26) =22313a(27) =4683a(28) =47293a(29) =47293