Number of self-inverse permutations on n letters, also known as involutions; number of standard Young tableaux with n cells.

A000085

Number of self-inverse permutations on n letters, also known as involutions; number of standard Young tableaux with n cells.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =26a(6) =76a(7) =232a(8) =764a(9) =2620a(10) =9496a(11) =35696a(12) =140152a(13) =568504a(14) =2390480a(15) =10349536a(16) =46206736a(17) =211799312a(18) =997313824a(19) =4809701440a(20) =23758664096a(21) =119952692896a(22) =618884638912

External references