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A304944
a(0) = 0, a(1) = 1 and a(n) = 6*a(n-1)/(n-1) + 16*a(n-2) for n > 1.
2
0, 1, 6, 34, 164, 790, 3572, 16212, 71048, 312678, 1345220, 5809980, 24692600, 105305980, 443684360, 1875046120, 7848968208, 32944100998, 137210821092, 572842556332, 2376270786840, 9878362137364, 40842721771544, 169192718317336, 697620779210096
OFFSET
0,3
COMMENTS
Let a(0) = 0, a(1) = 1 and a(n) = 2*m*a(n-1)/(n-1) + k^2*a(n-2) for n > 1, then the g.f. is x/(2*m) * d/dx ((1 + k*x)/(1 - k*x))^(m/k).
LINKS
FORMULA
a(n) = n*A304941(n)/6.
G.f.: x/(1-4*x)^2 * ((1-4*x)/(1+4*x))^(1/4).
MATHEMATICA
CoefficientList[Series[x/((1-4*x)^(7/4)*(1+4*x)^(1/4)), {x, 0, 40}], x] (* G. C. Greubel, Jun 07 2023 *)
PROG
(Magma) [n le 2 select n-1 else 2*(3*Self(n-1) + 8*(n-2)*Self(n-2))/(n-2): n in [1..40]]; // G. C. Greubel, Jun 07 2023
(SageMath)
@CachedFunction
def a(n): # b = A304944
if n<2: return n
else: return 2*(3*a(n-1) + 8*(n-1)*a(n-2))//(n-1)
[a(n) for n in range(41)] # G. C. Greubel, Jun 07 2023
CROSSREFS
Sequence in context: A086934 A009469 A222190 * A344717 A266359 A198765
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 22 2018
STATUS
approved