

A129532


3n(n1)4^(n2).


4



0, 0, 6, 72, 576, 3840, 23040, 129024, 688128, 3538944, 17694720, 86507520, 415236096, 1962934272, 9160359936, 42278584320, 193273528320, 876173328384, 3942779977728, 17626545782784, 78340203479040, 346346162749440
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OFFSET

0,3


COMMENTS

Number of inversions in all 4ary words of length n on {0,1,2,3}. Example: a(2)=6 because each of the words 10,20,30,21,31,32 has one inversion and the words 00,01,02,03,11,12,13,22,23,33 have no inversions. a(n)=Sum(k*A129531(n,k),k>=0). a(n)=6*A038845(n2).


LINKS



FORMULA

G.f.=6x^2/(14x)^3.


MAPLE

seq(3*n*(n1)*4^(n2), n=0..25);


MATHEMATICA

Table[3n(n1)4^(n2), {n, 0, 30}] (* or *) LinearRecurrence[{12, 48, 64}, {0, 0, 6}, 30] (* Harvey P. Dale, May 25 2018 *)


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



