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%I #18 May 11 2021 01:54:14
%S 1,257,7625597484988,340282366920938463463374607431768276993,
%T 2350988701644575015937473074444491355637331113544175043017503412556834518909454345703126
%N a(n) = Sum_{d|n} d^(d^2 * n).
%C The next term has 169 digits. - _Harvey P. Dale_, Feb 29 2020
%F L.g.f.: -log(Product_{k>=1} (1 - (k^(k^2)*x)^k)^(1/k)) = Sum_{k>=1} a(k)*x^k/k.
%t Table[Total[#^(#^2 n)&/@Divisors[n]],{n,5}] (* _Harvey P. Dale_, Feb 29 2020 *)
%t a[n_] := DivisorSum[n, #^(n * #^2) &]; Array[a, 5] (* _Amiram Eldar_, May 11 2021 *)
%o (PARI) {a(n) = sumdiv(n, d, d^(d^2*n))}
%o (PARI) N=10; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-(k^k^2*x)^k)^(1/k)))))
%Y Column k=3 of A308676.
%Y Cf. A023887, A055225, A308670.
%K nonn
%O 1,2
%A _Seiichi Manyama_, Jun 16 2019
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