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!)
A030507 Graham-Sloane-type lower bound on the size of a ternary (n,3,7) constant-weight code. 1
9, 61, 243, 732, 1837, 4056, 8136, 15149, 26571, 44374, 71125, 110094, 165376, 242014, 346136, 485103, 667662, 904109, 1206463, 1588650, 2066688, 2658897, 3386099, 4271843, 5342629, 6628148, 8161525, 9979578, 12123079, 14637028 (list; graph; refs; listen; history; text; internal format)
OFFSET
7,1
LINKS
Patric R. J. Östergård, Mattias Svanström, Ternary Constant Weight Codes, The Electronic Journal of Combinatorics, Volume 9 (2002), Research Paper #R41.
M. Svanström, A lower bound for ternary constant weight codes, IEEE Trans. on Information Theory, Vol. 43, pp. 1630-1632, Sep. 1997.
Mattias Svanström, A Class of Perfect Ternary Constant-Weight Codes, Designs, Codes and Cryptography, Volume 18, Issue 1-3 , pp 223-229.
FORMULA
a(n) = ceiling (binomial (n, w) * 2^w / (2*n + 1)) for w = 7.
MAPLE
A:= n -> ceil(binomial(n, 7)*2^7/(2*n+1)):
map(A, [$7 .. 60]); # Robert Israel, Jun 22 2015
CROSSREFS
Sequence in context: A159037 A138589 A058777 * A172208 A202660 A202120
KEYWORD
nonn
AUTHOR
Mattias Svanstrom (mattias(AT)isy.liu.se)
EXTENSIONS
Formula edited by Robert Israel, Jun 22 2015
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 April 17 01:50 EDT 2024. Contains 371756 sequences. (Running on oeis4.)