Number of n-step mirror-symmetrical self-avoiding walks on the square lattice.

Terms

a(0) =4a(1) =12a(2) =12a(3) =28a(4) =28a(5) =76a(6) =76a(7) =188a(8) =196a(9) =516a(10) =524a(11) =1292a(12) =1356a(13) =3500a(14) =3596a(15) =8908a(16) =9380a(17) =23940a(18) =24796a(19) =61500a(20) =64900a(21) =164612a(22) =171244a(23) =424940a(24) =449140a(25) =1134772a(26) =1184204a(27) =2939212a(28) =3109644a(29) =7834764