Number of peaks at odd 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).

A166292

Number of peaks at odd 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) =2a(3) =5a(4) =12a(5) =29a(6) =72a(7) =181a(8) =460a(9) =1178a(10) =3030a(11) =7815a(12) =20188a(13) =52193a(14) =134992a(15) =349205a(16) =903398a(17) =2337135a(18) =6046310a(19) =15642402a(20) =40469824a(21) =104708914a(22) =270937964a(23) =701129755a(24) =1814581514a(25) =4696886211a(26) =12159165336a(27) =31481922733a(28) =81523933604a(29) =211143257951

External references