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A154604 Hankel transform of reduced tangent numbers. 2
1, 1, 3, 54, 9720, 26244000, 1488034800000, 2362404048480000000, 135019896025206528000000000, 347259290825980971841536000000000000, 49121618545275670528799969525760000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Hankel transform of A002105 (with interpolated zeros). Hankel transform of A154603.

LINKS

Table of n, a(n) for n=0..10.

P. Barry, A Note on Three Families of Orthogonal Polynomials defined by Circular Functions, and Their Moment Sequences, Journal of Integer Sequences, Vol. 15 (2012), #12.7.2. - N. J. A. Sloane, Dec 27 2012

FORMULA

a(n) = Product_{k=1..n} C(k+1,2)^(n-k+1).

CROSSREFS

Sequence in context: A157568 A156911 A214006 * A188798 A334248 A193256

Adjacent sequences:  A154601 A154602 A154603 * A154605 A154606 A154607

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Jan 12 2009

STATUS

approved

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Last modified May 5 17:07 EDT 2021. Contains 343572 sequences. (Running on oeis4.)