Number of perfect matchings in the graph C_4 X C_n.

Terms

a(0) =50a(1) =272a(2) =722a(3) =3108a(4) =10082a(5) =39952a(6) =140450a(7) =537636a(8) =1956242a(9) =7379216a(10) =27246962a(11) =102144036a(12) =379501250a(13) =1418981392a(14) =5285770562a(15) =19742287908a(16) =73621286642a(17) =274848860432