login
Product_{n>=1} (1 + x^n)^(a(n)/n!) = 1 + sinh(x).
6

%I #6 May 22 2022 08:54:41

%S 1,0,1,-4,21,-76,1023,-12160,65145,-602416,10925883,-120444160,

%T 1994183205,-21404165056,372390766023,-12580544512000,158096182329585,

%U -2119447579092736,64115697136312563,-1412937791690260480,27389518837925527965,-616988361649163447296,19391677044464348893503

%N Product_{n>=1} (1 + x^n)^(a(n)/n!) = 1 + sinh(x).

%F E.g.f.: Sum_{k>=1} A067856(k) * log(1 + sinh(x^k)) / k.

%t b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[c[i], j] b[n - i j, i - 1], {j, 0, n/i}]]]; c[n_] := c[n] = Mod[n, 2]/n! - b[n, n - 1]; a[n_] := n! c[n]; Table[a[n], {n, 1, 23}]

%Y Cf. A067856, A353608, A353910, A354056, A354171, A354173, A354174, A354175, A354176.

%K sign

%O 1,4

%A _Ilya Gutkovskiy_, May 18 2022