Number of length-5 0..n arrays with no following elements larger than the first repeated value.

Terms

a(0) =21a(1) =160a(2) =712a(3) =2285a(4) =5921a(5) =13216a(6) =26440a(7) =48657a(8) =83845a(9) =137016a(10) =214336a(11) =323245a(12) =472577a(13) =672680a(14) =935536a(15) =1274881a(16) =1706325a(17) =2247472a(18) =2918040a(19) =3739981a(20) =4737601a(21) =5937680a(22) =7369592a(23) =9065425a(24) =11060101a(25) =13391496a(26) =16100560a(27) =19231437a(28) =22831585