login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A225070 Least decagonal (10-gonal) number that is the product of n decagonal numbers greater than 1. 7
10, 69300, 9729720, 4257000, 967412160, 4104100000, 1408951239696000, 59860503846000000, 1542547619019487080000, 39054496014386012160000, 450510331438947780000000 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
Let dec(n) = n*(4n-3). Then
a(1) = 10 = dec(2).
a(2) = 69300 = dec(132) = dec(2) * dec(42).
a(3) = 9729720 = dec(1560) = dec(3) * dec(4) * dec(42).
a(4) = 4257000 = dec(1032) = dec(2)^3 * dec(33).
a(5) = 967412160 = dec(15552) = dec(2) * dec(3) * dec(4) * dec(8) * dec(9).
a(6) = 4104100000 = dec(32032) = dec(2)^3 * dec(4) * dec(7) * dec(11).
CROSSREFS
Cf. A001107 (decagonal numbers).
Cf. A212616, A212617, A225066-A225069 (3-, 5- to 9-gonal cases).
Sequence in context: A260797 A055310 A048832 * A115673 A225720 A013792
KEYWORD
nonn,more
AUTHOR
T. D. Noe, May 01 2013
EXTENSIONS
Corrected a(6) and added a(7)-a(11) by Lars Blomberg, Sep 20 2013
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)