A346398 Expansion of e.g.f. -log(1 - x) * exp(-3*x).
0, 1, -5, 20, -72, 249, -825, 2736, -8568, 29385, -74709, 417636, 698544, 21853233, 244181223, 3608612208, 54277152624, 878859416817, 15072037479099, 273539358115092, 5235734703888648, 105419854939796937, 2227408664800976487, 49278475088626210704, 1139260699549648412856
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..451
Programs
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Mathematica
nmax = 24; CoefficientList[Series[-Log[1 - x] Exp[-3 x], {x, 0, nmax}], x] Range[0, nmax]! Table[n! Sum[(-3)^k/((n - k) k!), {k, 0, n - 1}], {n, 0, 24}]
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PARI
a_vector(n) = my(v=vector(n+1, i, if(i==2, 1, 0))); for(i=2, n, v[i+1]=(i-4)*v[i]+3*(i-1)*v[i-1]+(-3)^(i-1)); v; \\ Seiichi Manyama, May 27 2022
Formula
a(n) = n! * Sum_{k=0..n-1} (-3)^k / ((n-k) * k!).
a(0) = 0, a(1) = 1, a(n) = (n-4) * a(n-1) + 3 * (n-1) * a(n-2) + (-3)^(n-1). - Seiichi Manyama, May 27 2022
a(n) ~ exp(-3) * (n-1)!. - Vaclav Kotesovec, Jun 08 2022