OFFSET
1,2
COMMENTS
Generalized Bell numbers B(4,1;n).
REFERENCES
P. Blasiak, K. A. Penson and A. I. Solomon, The general boson normal ordering problem, Phys. Lett. A 309 (2003) 198-205.
LINKS
Wolfdieter Lang, On generalizations of the Stirling number triangles, J. Integer Seqs., Vol. 3 (2000), #00.2.4.
P. Blasiak, K. A. Penson and A. I. Solomon, The general boson normal ordering problem, arXiv:quant-ph/0402027, 2004.
P. Blasiak, K. A. Penson and A. I. Solomon, Combinatorial coherent states via normal ordering of bosons, arXiv:quant-ph/0311033, 2003.
FORMULA
E.g.f.: exp(-1+1/(1-3*x)^(1/3))-1.
a(n) = D^n(exp(x)) evaluated at x = 0, where D is the operator (1+x)^4*d/dx. Cf. A000110, A000262, A049118 and A049120. - Peter Bala, Nov 25 2011
a(n) = (1/e) * (-3)^n * n! * Sum_{k>=0} binomial(-k/3,n)/k!. - Seiichi Manyama, Jan 17 2025
MATHEMATICA
Drop[CoefficientList[Series[Exp[-1+1/(1-3*x)^(1/3)]-1, {x, 0, 19}], x]Range[0, 19]!, 1] (* Stefano Spezia, Mar 31 2025 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
STATUS
approved
