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Search: id:A099555
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| A099555 |
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Triangle, read by rows, where T(n,k) = (n-[k/2])^k and [k/2] is the integer floor of k/2, for 2n>=k>=0. |
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+0 4
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| 1, 1, 1, 1, 2, 1, 1, 1, 3, 4, 8, 1, 1, 1, 4, 9, 27, 16, 32, 1, 1, 1, 5, 16, 64, 81, 243, 64, 128, 1, 1, 1, 6, 25, 125, 256, 1024, 729, 2187, 256, 512, 1, 1, 1, 7, 36, 216, 625, 3125, 4096, 16384, 6561, 19683, 1024, 2048, 1, 1, 1, 8, 49, 343, 1296, 7776, 15625, 78125, 65536
(list; table; graph; listen)
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OFFSET
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0,5
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COMMENT
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Row functions in y are given by: R_n(y)=Sum_{k=0..2n} (n-[k/2])^k*y^k/k!. Evaluated at y=1, the asymptotic behavior of the rows is given by: R_n(1) ~ c*r^n where c = (r+sqrt(r))/(1+2*sqrt(r)) = 0.8957126... and r = 2.0207473586... satisfies r = exp(1/sqrt(r)) - see A099554 for the decimal expansion of this constant.
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FORMULA
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E.g.f.: ((1-x*cosh(sqrt(x)*y))+sqrt(x)*sinh(sqrt(x)*y))/(1+x^2-2*x*cosh(sqrt(x)*y)).
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EXAMPLE
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The asymptotic behavior can be demonstrated at the 4-th row function:
R_4(y) = 1+4y+9y^2/2!+27y^3/3!+16y^4/4!+32y^5/5!+y^6/6!+y^7/7!;
R_4(1) = 14.93492... = (0.895684...)*r^4, where r = 2.0207473586...
Rows begin:
[1]
[1,1],
[1,2,1,1],
[1,3,4,8,1,1],
[1,4,9,27,16,32,1,1],
[1,5,16,64,81,243,64,128,1,1],
[1,6,25,125,256,1024,729,2187,256,512,1,1],
[1,7,36,216,625,3125,4096,16384,6561,19683,1024,2048,1,1],...
which can be derived from the square array A003992:
[1,0,0,0,0,0,0,0,...],
[1,1,1,1,1,1,1,1,...],
[1,2,4,8,16,32,64,...],
[1,3,9,27,81,243,729,...],
[1,4,16,64,256,1024,4096,...],
[1,5,25,125,625,3125,15625,...],...
by shifting each column k down by [k/2] rows,
and omitting the zeros coming from row 0 of A003992.
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PROGRAM
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(PARI) T(n, k)=(n-k\2)^k
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CROSSREFS
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Cf. A003992, A099554, A099556.
Sequence in context: A122867 A124775 A140075 this_sequence A124530 A070914 A124560
Adjacent sequences: A099552 A099553 A099554 this_sequence A099556 A099557 A099558
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KEYWORD
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nonn,tabl
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Oct 22 2004
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