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A076008 Second column of triangle A075504. 3
1, 27, 567, 10935, 203391, 3720087, 67493007, 1219657095, 21996874431, 396331160247, 7137447668847, 128505439098855, 2313380333315871, 41643387865514007, 749603858371707087, 13493075341822822215 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
The e.g.f. given below is Sum_{m=0..1} (A075513(3,m)*exp(9*(m+1)*x)).
LINKS
FORMULA
a(n) = A075504(n+2, 2) = (9^n)*S2(n+2, 2) with S2(n, m) := A008277(n, m) (Stirling2).
a(n) = -9^n + 2*18^n.
G.f.: 1/((1-9*x)*(1-18*x)).
E.g.f.: (d^2/dx^2)(((exp(9*x)-1)/9)^2)/2! = -exp(9*x) + 2*exp(18*x).
a(0)=1, a(1)=27, a(n) = 27*a(n-1) - 162*a(n-2). - Harvey P. Dale, Dec 01 2015
MATHEMATICA
CoefficientList[Series[1/((1-9x)(1-18x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{27, -162}, {1, 27}, 30] (* Harvey P. Dale, Dec 01 2015 *)
CROSSREFS
Sequence in context: A347591 A267544 A061914 * A232944 A185891 A185883
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Oct 02 2002
STATUS
approved

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Last modified April 16 07:08 EDT 2024. Contains 371698 sequences. (Running on oeis4.)