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a(n) = (n+1)^(n-1)/(n+2) + (-1)^n/(n+2).
2

%I #10 Dec 07 2019 12:18:24

%S 1,0,1,3,21,185,2101,29127,478297,9090909,196495641,4762874171,

%T 128011456717,3779594158353,121637191772461,4238682002231055,

%U 159023502861656433,6391554268241802725,274019342889240109297

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

%o (Sage) [abs(gaussian_binomial(n,1,-(n+2))) for n in range(-1,18)] # _Zerinvary Lajos_, May 31 2009

%Y Cf. A083062, A081216, A081209.

%K easy,nonn

%O 0,4

%A _Paul Barry_, Apr 20 2003