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A084157
a(n) = 8*a(n-1) - 16*a(n-2) + 12*a(n-4) with a(0)=0, a(1)=1, a(2)=4, a(3)=22.
2
0, 1, 4, 22, 112, 556, 2704, 13000, 62080, 295312, 1401664, 6644320, 31472896, 149017792, 705395968, 3338614912, 15800258560, 74772443392, 353840161792, 1674425579008, 7923565146112, 37494981225472, 177428889407488
OFFSET
0,3
COMMENTS
Binomial transform of A084156.
FORMULA
a(n) = (A083881(n) - A026150(n))/2.
a(n) = 8*a(n-1) - 16*a(n-2) + 12*a(n-4).
a(n) = ((3+sqrt(3))^n + (3-sqrt(3))^n - (1+sqrt(3))^n - (1-sqrt(3))^n)/4.
G.f.: x*(1-4*x+6*x^2)/((1-2*x-2*x^2)*(1-6*x+6*x^2)).
E.g.f.: exp(2*x)*sinh(x)*cosh(sqrt(3)*x).
From G. C. Greubel, Oct 11 2022: (Start)
a(2*n) = A003462(n)*A026150(2*n) = A003462(n)*A080040(2*n)/2.
a(2*n+1) = (1/2)*(3^(n+1)*A002605(2*n+1) - A026150(2*n+1)). (End)
MATHEMATICA
LinearRecurrence[{8, -16, 0, 12}, {0, 1, 4, 22}, 30] (* Harvey P. Dale, Feb 19 2017 *)
PROG
(Magma) I:=[0, 1, 4, 22]; [n le 4 select I[n] else 8*Self(n-1) -16*Self(n-2) +12*Self(n-4): n in [1..41]]; // G. C. Greubel, Oct 11 2022
(SageMath)
A083881 = BinaryRecurrenceSequence(6, -6, 1, 3)
A026150 = BinaryRecurrenceSequence(2, 2, 1, 1)
def A084157(n): return (A083881(n) - A026150(n))/2
[A084157(n) for n in range(41)] # G. C. Greubel, Oct 11 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, May 16 2003
STATUS
approved