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A089507
Second column of triangle A089504 and second column of array A078741 divided by 18.
4
1, 30, 756, 18360, 441936, 10614240, 254788416, 6115201920, 146766525696, 3522406694400, 84537821131776, 2028908069959680, 48693795855814656, 1168651113600245760, 28047626804770062336, 673143043784666480640
OFFSET
0,2
COMMENTS
Convolution of A000400 (powers of 6) with A009968 (powers of 24).
FORMULA
G.f.: 1/((1-3*2*1*x)*(1-4*3*2*x)).
a(n) = A089504(n+2, 2), n>=0.
a(n) = (4*(4*3*2)^n - (3*2*1)^n)/3 = (2^n)*(2^(2*(n+1))-1)*3^(n-1).
a(n) = 6^n*(4^(n+1)-1)/3. - Vincenzo Librandi, Oct 18 2017
MATHEMATICA
CoefficientList[Series[1/((1-6x)(1-24x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{30, -144}, {1, 30}, 20] (* Harvey P. Dale, Sep 25 2017 *)
PROG
(Magma) [6^n*(4^(n+1)-1)/3: n in [0..15]]; // Vincenzo Librandi, Oct 18 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Dec 01 2003
STATUS
approved