A379685 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-2*x) * (1 - x*exp(x)) ).
1, 3, 30, 551, 15028, 547717, 25068058, 1383323517, 89443699176, 6634682537993, 555501170856934, 51828125728865257, 5332620999430989244, 599894268098223894525, 73253745510185331985842, 9650159930850877102454693, 1364228585624978795929566928, 206008264557747708717576118417
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, (3*n-k+2)^k*(2*n-k)!/(k!*(n-k)!))/(n+1);
Formula
a(n) = (1/(n+1)) * Sum_{k=0..n} (3*n-k+2)^k * (2*n-k)!/(k! * (n-k)!).