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A100517 Denominator of Sum_{k=0..n} 1/C(n,k)^2. 4
1, 1, 4, 9, 72, 10, 3600, 1575, 2800, 1764, 14112, 13475, 34927200, 2316600, 192192, 4459455, 4994589600, 262061800, 735869534400, 17476901442, 422721728, 353723760, 31127690880, 10150725585, 59637542956992, 2205530434800, 155748568976000, 50956005028500 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

REFERENCES

H. W. Gould, Combinatorial Identities, Morgantown, 1972, p. 50.

LINKS

Table of n, a(n) for n=0..27.

EXAMPLE

1, 2, 9/4, 20/9, 155/72, 21/10, 7441/3600, 3224/1575, 5697/2800, 3575/1764, 28523/14112, 27183/13475, 70357417/34927200, 4661447/2316600, ... = A100516/A100517

MATHEMATICA

Table[Sum[1/Binomial[n, k]^2, {k, 0, n}], {n, 0, 30}]//Denominator (* Harvey P. Dale, Apr 01 2019 *)

CROSSREFS

Cf. A100516, A046825.

Sequence in context: A220189 A122956 A041777 * A327579 A041597 A041030

Adjacent sequences:  A100514 A100515 A100516 * A100518 A100519 A100520

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Nov 25 2004

STATUS

approved

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Last modified October 26 06:08 EDT 2021. Contains 348257 sequences. (Running on oeis4.)