|
%I
%S 45,3960,279720,16798320,839991600,33599966400,1007999899200,
%T 20159999798400,201599999798400
%N a(n) = sum of n-digit numbers with distinct nonzero digits.
%D H. E. Dudeney, Amusements in Mathematics, Dover, NY, 1917, pp. 17, 160.
%H H. E. Dudeney, <a href="http://www.gutenberg.org/files/16713/16713-h/16713-h.htm">Amusements in Mathematics</a> [Gutenberg Project Etext]
%F a(n) = 5*(10^n - 1)*8!/(9 - n)!.
%t Table[5*(10^n - 1)*8!/(9 - n)!, {n, 9}]
%o (MAGMA) [ 5*(10^n-1)*Factorial(8)/Factorial(9-n) : n in [1..9]]
%o (PARI) vector(9, n, 5*(10^n-1)*8!/(9-n)!)
%K base,easy,fini,full,nonn
%O 1,1
%A _Arkadiusz Wesolowski_, Jun 23 2012
|
