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A276636 Number of up-down sequences with 3 copies each of 1,2,...,n. 1
1, 0, 1, 12, 761, 87336, 18528505, 6376563600, 3338759427857, 2524750777586976, 2648982517454387281, 3733860677541032881728, 6885982148044369769847497, 16251753910337100552968630400 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..13.

EXAMPLE

a(3) = 12: 121313232, 121323132, 121323231, 131213232, 132312132, 132323121, 231213132, 231213231, 231312132, 231323121, 232312131, 232313121.

a(4) = 761: 121213243434, 121214343423, 121313242434, 121313243424, ..., 343424121213, 343424121312, 343424131212, 343434121212.

CROSSREFS

Column k=3 of A275784.

Sequence in context: A317337 A089036 A273033 * A284769 A201246 A291999

Adjacent sequences:  A276633 A276634 A276635 * A276637 A276638 A276639

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Sep 08 2016

STATUS

approved

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Last modified May 21 21:43 EDT 2022. Contains 353929 sequences. (Running on oeis4.)