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A307031 n to the power n double factorial, n^(n!!).

%I A307031 #10 Feb 16 2025 08:33:55
%S A307031 1,4,27,65536,30517578125,22452257707354557240087211123792674816,
%T A307031 54361846697263307560529495055267343940077014163990039113495978834700158362117849904436807
%N A307031 n to the power n double factorial, n^(n!!).
%C A307031 The next term -- a(8) -- has 347 digits. - _Harvey P. Dale_, Aug 11 2021
%H A307031 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DoubleFactorial.html">Double Factorial</a>
%F A307031 a(n) = n^(n!!).
%t A307031 Table[n^n!!,{n,7}] (* _Harvey P. Dale_, Aug 11 2021 *)
%o A307031 (Python)
%o A307031 def doublefactorial(n):
%o A307031      if n <= 0:
%o A307031          return 1
%o A307031      else:
%o A307031          return n * doublefactorial(n-2)
%o A307031 for n in range(1,m):
%o A307031     print(n**doublefactorial(n))
%Y A307031 Cf. A254866, A053986.
%K A307031 nonn
%O A307031 1,2
%A A307031 _Mark Stander_, Mar 20 2019