Number of idempotent 5 X 5 0..n matrices of rank 4.

Terms

a(0) =155a(1) =805a(2) =2555a(3) =6245a(4) =12955a(5) =24005a(6) =40955a(7) =65605a(8) =99995a(9) =146405a(10) =207355a(11) =285605a(12) =384155a(13) =506245a(14) =655355a(15) =835205a(16) =1049755a(17) =1303205a(18) =1599995a(19) =1944805a(20) =2342555a(21) =2798405a(22) =3317755a(23) =3906245a(24) =4569755a(25) =5314405a(26) =6146555a(27) =7072805a(28) =8099995a(29) =9235205