Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A011957
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A011957 Number of ZnS polytypes that repeat after n layers. +0
1
0, 1, 1, 1, 1, 2, 3, 6, 10, 18, 31, 59, 105, 198, 365, 688, 1285, 2438, 4599, 8755, 16647, 31806, 60787, 116570, 223696, 430290, 828514, 1598025, 3085465, 5965612, 11545611, 22370304, 43383539, 84216330, 163617801, 318148208 (list; graph; listen)
OFFSET

1,6

COMMENT

Also the number of orbits of the symmetric group S3 action on irreducible polynomials of degree n>1 over GF(2). [From Jean-Francis Michon, Philippe Ravache (philippe.ravache(AT)univ-rouen.fr), Oct 04 2009]

REFERENCES

T. J. McLarnan, The numbers of polytypes ..., Zeits. Krist. 155, 269-291 (1981).

FORMULA

a(n) = 1 if n=2, A000048(n) + A165920(n) + A165921(n) if n>2. [From Jean-Francis Michon, Philippe Ravache (philippe.ravache(AT)univ-rouen.fr), Oct 04 2009]

CROSSREFS

A000048 is the number of 3-elements orbits, A165920 is the number of 2-elements orbits and A165921 is the number of 6-elements orbits. [From Jean-Francis Michon, Philippe Ravache (philippe.ravache(AT)univ-rouen.fr), Oct 04 2009]

Sequence in context: A023359 A082482 A066000 this_sequence A019436 A147852 A061279

Adjacent sequences: A011954 A011955 A011956 this_sequence A011958 A011959 A011960

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


AT&T Labs Research