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%I #12 Feb 11 2024 16:39:29
%S 1,0,-1,-2,15,759374,191749544167774320464809980317709375
%N a(1) = 1, for n >= 2: a(n) = a(n-1)^(n-1) - 1.
%C a(8) has 247 digits.
%C a(9) has 1976 digits. - _Harvey P. Dale_, Feb 11 2024
%e For n = 5: a(5) = (-2)^(5-1) - 1 = 15.
%t nxt[{n_,a_}]:={n+1,a^n-1}; NestList[nxt,{1,1},7][[;;,2]] (* _Harvey P. Dale_, Feb 11 2024 *)
%K sign
%O 1,4
%A _Jaroslav Krizek_, Nov 03 2010