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A319218 Expansion of e.g.f. Product_{k>=1} (1 - x^k/(k - 1)!). 1

%I #8 Jan 09 2019 09:19:18

%S 1,-1,-2,3,8,75,-216,-175,-3816,-36225,189800,325149,2375460,25547951,

%T 386162126,-3290670825,-6316583056,-59290501809,-310987223208,

%U -4836373835707,-86500419684420,1119358992256239,3043733432729198,26408738842522959,169835931388147464

%N Expansion of e.g.f. Product_{k>=1} (1 - x^k/(k - 1)!).

%F E.g.f.: exp(-Sum_{k>=1} Sum_{j>=1} x^(j*k)/(k*((j - 1)!)^k)).

%p seq(n!*coeff(series(mul((1 - x^k/(k - 1)!),k=1..100),x=0,25),x,n),n=0..24); # _Paolo P. Lava_, Jan 09 2019

%t nmax = 24; CoefficientList[Series[Product[(1 - x^k/(k - 1)!), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!

%t nmax = 24; CoefficientList[Series[Exp[-Sum[Sum[x^(j k)/(k (j - 1)!^k), {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!

%t a[n_] := a[n] = If[n == 0, 1, (n - 1)! Sum[Sum[-d (d - 1)!^(-k/d), {d, Divisors[k]}] a[n - k]/(n - k)!, {k, 1, n}]]; Table[a[n], {n, 0, 24}]

%Y Cf. A032299, A076900, A185895, A319219.

%K sign

%O 0,3

%A _Ilya Gutkovskiy_, Sep 13 2018

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Last modified March 28 14:33 EDT 2024. Contains 371254 sequences. (Running on oeis4.)