Number of s in {1,...,n}^n having shortest run with the same value of length 4.

Terms

a(0) =4a(1) =0a(2) =0a(3) =0a(4) =56a(5) =144a(6) =180a(7) =220a(8) =1716a(9) =5928a(10) =14560a(11) =26880a(12) =97680a(13) =344352a(14) =978588a(15) =2346120a(16) =7444580a(17) =25763640a(18) =79547622a(19) =213434848a(20) =663024312a(21) =2288434800a(22) =7496808800a(23) =21967834824a(24) =68476484916a(25) =235311849416a(26) =802176548700