A344215 - OEIS

A344215

a(n) = n*(3^(n-1) - 2^(n-1)).

0, 0, 2, 15, 76, 325, 1266, 4655, 16472, 56745, 191710, 638275, 2101188, 6855485, 22205834, 71498775, 229058224, 730680145, 2322163638, 7356008555, 23234743580, 73200452325, 230081633122, 721667902015, 2259234965256, 7060318981625, 22028631430286, 68628565425555, 213512971483252

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OFFSET

0,3

COMMENTS

a(n) is the number of quaternary strings of length n that contain one 0 and at least one 1.

For ternary strings with this property see A058877; for binary strings see A199969.

LINKS

Table of n, a(n) for n=0..28.

Index entries for linear recurrences with constant coefficients, signature (10,-37,60,-36).

FORMULA

E.g.f.: x*(exp(3*x) - exp(2*x)).

G.f.: x^2*(2 - 5*x)/(1 - 5*x + 6*x^2)^2. - Stefano Spezia, May 12 2021