Number of set partitions of [n] into exactly four blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.

A274868

Number of set partitions of [n] into exactly four blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.

Terms

    a(0) =1a(1) =2a(2) =7a(3) =14a(4) =35a(5) =70a(6) =155a(7) =310a(8) =651a(9) =1302a(10) =2667a(11) =5334a(12) =10795a(13) =21590a(14) =43435a(15) =86870a(16) =174251a(17) =348502a(18) =698027a(19) =1396054a(20) =2794155a(21) =5588310a(22) =11180715a(23) =22361430a(24) =44731051a(25) =89462102a(26) =178940587a(27) =357881174a(28) =715795115a(29) =1431590230

External references