884520

Appears in sequences

• Nonuple factorial, 9-factorial, n!9, n!!!!!!!!!.at n=39A114806
• Partial products of successive terms of A017197.at n=5A144758
• Triangular array read by rows: T(n,k) is the number of functions f:{1,2,...,n} -> {1,2,...,n} that have exactly k 2-cycles for n >= 0 and 0 <= k <= floor(n/2).at n=28A185025
• G.f.: Sum_{n>=0} x^n * (1 + n^2*x)^n / (1 + x + n^2*x^2)^n.at n=9A210443
• Numbers n such that sigma(n+sigma(n)) = 5*sigma(n).at n=20A246912
• Wiener index of the n X n rook complement graph.at n=35A292058
• Numbers k such that the squarefree kernel of sigma(k) is equal to the squarefree kernel of 2*k.at n=43A332208
• Square table read by downward antidiagonals: n-th row has e.g.f. (1-9*x)^(-n/9).at n=39A392037