Number of nX4 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X5 binary array having determinant equal to one, with rows and columns of the latter in nondecreasing lexicographic order.
A227639
Number of nX4 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X5 binary array having determinant equal to one, with rows and columns of the latter in nondecreasing lexicographic order.
Terms
- a(0) =4a(1) =23a(2) =127a(3) =667a(4) =3202a(5) =13740a(6) =53575a(7) =192191a(8) =640831a(9) =2002960a(10) =5909556a(11) =16555375a(12) =44257697a(13) =113385871a(14) =279415526a(15) =664438386a(16) =1528929898a(17) =3412860357a(18) =7406164606a(19) =15655003700a(20) =32288642035a(21) =65081639197a(22) =128377414029a(23) =248137470904
External references
- oeis: A227639