Number of derangements of n elements with one pair repeated exactly once (e.g., "ABABCDEF").

A140526

Number of derangements of n elements with one pair repeated exactly once (e.g., "ABABCDEF").

Terms

    a(0) =1a(1) =4a(2) =29a(3) =230a(4) =2033a(5) =19744a(6) =209581a(7) =2418226a(8) =30173825a(9) =405194012a(10) =5830108061a(11) =89520810334

External references