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A206307
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a(n) = ((2*n+2)*(2*n+3) - 1)*a(n-1) + 2*n*(2*n+1)*a(n-2), a(0)=0, a(1)=6.
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3
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0, 6, 246, 17718, 1948974, 304039950, 63848389494, 17366761942374, 5939432584291902, 2494561685402598846, 1262248212813715016070, 757348927688229009642006, 531658947237136764768688206, 431707065156555052992174823278
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OFFSET
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0,2
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COMMENTS
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The numerators of the fractions limiting to the value of A206530.
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REFERENCES
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E. W. Cheney, Introduction to Approximation Theory, McGraw-Hill, Inc., 1966.
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LINKS
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FORMULA
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MATHEMATICA
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RecurrenceTable[{a[n]==((2n+3)(2n+2)-1)a[n-1]+2n(2n+1)a[n-2], a[0]==0, a[1]==6}, a, {n, 15}]
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PROG
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(Magma) [n le 2 select 6*(n-1) else (4*n^2+2*n-1)*Self(n-1) + 2*(n-1)*(2*n-1)*Self(n-2): n in [1..31]]; // G. C. Greubel, Dec 20 2022
(SageMath)
@CachedFunction
def a(n): return 6*n if (n<2) else (4*n^2+10*n+5)*a(n-1) + 2*n*(2*n+1)*a(n-2)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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