A367839 Expansion of e.g.f. 1/(2 + x - exp(3*x)).
1, 2, 17, 183, 2679, 48903, 1071621, 27394965, 800378019, 26307021483, 960739737777, 38595129840369, 1691405818822719, 80301792637126791, 4105701241574252445, 224912022483008478141, 13142159127790633537947, 815924005186398537216483
Offset: 0
Keywords
Programs
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PARI
a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=-i*v[i]+sum(j=1, i, 3^j*binomial(i, j)*v[i-j+1])); v;
Formula
a(0) = 1; a(n) = -n * a(n-1) + Sum_{k=1..n} 3^k * binomial(n,k) * a(n-k).