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a(n) = Product_{k=0..n} (n^5 + k^5).
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%I #16 Dec 04 2023 04:30:38

%S 0,2,67584,7924375800,2876035930521600,2693451205324687500000,

%T 5648896640332217707816550400,23819277009290664033936067933468800,

%U 185754160490281505676324140907107450880000,2507604631016507710974687639612411760216253760000

%N a(n) = Product_{k=0..n} (n^5 + k^5).

%C In general, for p>=1, Product_{k=0..n} (n^p + k^p) ~ sqrt(2) * n^(p*(n+1)) * exp(n*Sum_{j>=1} (-1)^(j+1) / (j*(1 + j*p))).

%F a(n) ~ 2^(2*n+1/2) * phi^(sqrt(5)*n) * n^(5*n+5) / exp((5-sqrt(phi)*Pi/5^(1/4))*n), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio.

%t Table[Product[n^5+k^5,{k,0,n}],{n,0,10}]

%Y Cf. A126804, A272244, A272246, A272247, A367823, A367833.

%Y Cf. A255435, A323543, A324438.

%K nonn,easy

%O 0,2

%A _Vaclav Kotesovec_, Apr 23 2016