Number of partitions of 112233...nn into n pairs.

A108704

Number of partitions of 112233...nn into n pairs.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =18a(4) =126a(5) =1110a(6) =12120a(7) =156660a(8) =2341500a(9) =39701340a(10) =752839920a(11) =15785181720a(12) =362606123880

External references