login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A204846 Irregular triangle read by rows in which row n lists algebraic prime factors of the repunit (10^n - 1)/9 (A002275(n)). 5
1, 1, 1, 11, 1, 3, 11, 37, 1, 11, 101, 3, 37, 11, 41, 271 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..16.

Samuel Yates, The Mystique of Repunits, Math. Mag. 51 (1978), 22-28.

EXAMPLE

Triangle begins: 1

1

1

11

1

3,11,37

1

11,101

3,37

11,41,271

...

CROSSREFS

Cf. A002275, A102380, A204845.

Sequence in context: A214676 A010198 A307245 * A127991 A110305 A010199

Adjacent sequences:  A204843 A204844 A204845 * A204847 A204848 A204849

KEYWORD

nonn,tabf,more

AUTHOR

N. J. A. Sloane, Jan 19 2012

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 April 18 01:48 EDT 2021. Contains 343072 sequences. (Running on oeis4.)