a(1) = 0, a(2) = 1, a(3) = 1, a(4) = 7; thereafter, a(n) = a(n-1) + (n-1)*a(n-2).

A086828

a(1) = 0, a(2) = 1, a(3) = 1, a(4) = 7; thereafter, a(n) = a(n-1) + (n-1)*a(n-2).

Terms

    a(0) =0a(1) =1a(2) =1a(3) =7a(4) =11a(5) =46a(6) =112a(7) =434a(8) =1330a(9) =5236a(10) =18536a(11) =76132a(12) =298564a(13) =1288280a(14) =5468176a(15) =24792376a(16) =112283192a(17) =533753584a(18) =2554851040a(19) =12696169136a(20) =63793189936a(21) =330412741792

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