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A026155
T(n,n-4), where T is the array in A026148.
0
1, 4, 16, 56, 189, 616, 1967, 6182, 19205, 59124, 180726, 549276, 1661646, 5007520, 15042722, 45068836, 134727499, 401991436, 1197519631, 3562523314, 10585937404, 31424706800, 93206486620, 276253350360, 818278951035, 2422518642516
OFFSET
4,2
FORMULA
Conjectures from Chai Wah Wu, Mar 23 2020: (Start)
a(n) = 12*a(n-1) - 53*a(n-2) + 90*a(n-3) + 26*a(n-4) - 256*a(n-5) + 160*a(n-6) + 224*a(n-7) - 203*a(n-8) - 84*a(n-9) + 77*a(n-10) + 14*a(n-11) - 7*a(n-12) for n > 15.
G.f.: x^4*(x - 1)^2*(x^6 - 6*x^5 - 13*x^4 + 8*x^3 + 8*x^2 - 6*x + 1)/((7*x^6 + 7*x^5 - 21*x^4 + 14*x^2 - 7*x + 1)*(x^6 - 3*x^5 - 5*x^4 + 8*x^3 + 4*x^2 - 5*x + 1)). (End)
CROSSREFS
First differences of A026329.
Sequence in context: A073388 A109634 A026126 * A025182 A057585 A333107
KEYWORD
nonn
STATUS
approved