login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A094261 a(n) = n(n-1)(n-3)(n-6)...(n-t), where t is the largest triangular number less than n; number of factors in the product is ceiling((sqrt(1+8*n)-1)/2). 0
1, 2, 6, 12, 40, 90, 168, 560, 1296, 2520, 4400, 14256, 32760, 64064, 113400, 187200, 586432, 1321920, 2560896, 4522000, 7484400, 11797632, 35784320, 78871968, 150480000, 263120000, 433060992, 681080400, 1033305728, 3044304000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

a(8) = 8*(8-1)*(8-3)*(8-6) = 8*7*5*2 = 560.

MAPLE

a:=n->product(n-k*(k+1)/2, k=0..ceil((sqrt(1+8*n)-1)/2)-1): seq(a(n), n=1..35); # Emeric Deutsch, Feb 03 2006

CROSSREFS

Cf. A057944, A094262.

Sequence in context: A123045 A280171 A327879 * A080497 A127724 A178008

Adjacent sequences:  A094258 A094259 A094260 * A094262 A094263 A094264

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Apr 26 2004

EXTENSIONS

Corrected and extended by Emeric Deutsch, Feb 03 2006

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 14 09:25 EDT 2019. Contains 327995 sequences. (Running on oeis4.)