Number of peaks at even level in all Dyck paths of semilength n with no UUU's and no DDD's, (U=(1,1), D=(1,-1)). These Dyck paths are counted by the secondary structure numbers (A004148).
A166294
Number of peaks at even level in all Dyck paths of semilength n with no UUU's and no DDD's, (U=(1,1), D=(1,-1)). These Dyck paths are counted by the secondary structure numbers (A004148).
Terms
- a(0) =0a(1) =1a(2) =4a(3) =12a(4) =34a(5) =92a(6) =242a(7) =628a(8) =1616a(9) =4138a(10) =10570a(11) =26970a(12) =68798a(13) =175545a(14) =448176a(15) =1145058a(16) =2927924a(17) =7493021a(18) =19191836a(19) =49195806a(20) =126205062a(21) =324000494a(22) =832371414a(23) =2139802870a(24) =5504256592a(25) =14166936063a(26) =36483006046a(27) =94000206216
External references
- oeis: A166294