A125599 - OEIS

%I #2 Mar 31 2012 13:20:34

%S 0,1,37,4161,1010101,432988561,290738012181,282578800148737,

%T 375973780484811925,657002506265664160401,1460516560427337565647925,

%U 4026980002567282984447709761,13491386325240318454518243016437

%N Quotient ((2n)^(2n-2)-1)/(2n+1)/(2n-1).

%F a(n) = A125598[2n-1]/(2n+1). a(n) = (A000272[2n]-1)/(2n+1)/(2n-1). a(n) = (b^(n-1)-1)/(b-1), for b = (2n)^2.

%t Table[(((2n)^(n-1))^2-1)/(2n+1)/(2n-1),{n,1,20}]

%Y Cf. A125598 = ((n+1)^(n-1)-1)/n. Cf. A000272 = n^(n-2).

%K nonn

%O 1,3

%A _Alexander Adamchuk_, Nov 26 2006