A030507 - OEIS

%I #9 Jun 22 2015 16:42:53

%S 9,61,243,732,1837,4056,8136,15149,26571,44374,71125,110094,165376,

%T 242014,346136,485103,667662,904109,1206463,1588650,2066688,2658897,

%U 3386099,4271843,5342629,6628148,8161525,9979578,12123079,14637028

%N Graham-Sloane-type lower bound on the size of a ternary (n,3,7) constant-weight code.

%H Robert Israel, <a href="/A030507/b030507.txt">Table of n, a(n) for n = 7..10000</a>

%H Patric R. J. Östergård, Mattias Svanström, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v9i1r41">Ternary Constant Weight Codes</a>, The Electronic Journal of Combinatorics, Volume 9 (2002), Research Paper #R41.

%H M. Svanström, <a href="http://dx.doi.org/10.1109/18.623164">A lower bound for ternary constant weight codes</a>, IEEE Trans. on Information Theory, Vol. 43, pp. 1630-1632, Sep. 1997.

%H Mattias Svanström, <a href="http://dx.doi.org/10.1023/A:1008361925021">A Class of Perfect Ternary Constant-Weight Codes</a>, Designs, Codes and Cryptography, Volume 18, Issue 1-3 , pp 223-229.

%F a(n) = ceiling (binomial (n, w) * 2^w / (2*n + 1)) for w = 7.

%p A:= n -> ceil(binomial(n,7)*2^7/(2*n+1)):

%p map(A, [$7 .. 60]); # _Robert Israel_, Jun 22 2015

%K nonn

%O 7,1

%A Mattias Svanstrom (mattias(AT)isy.liu.se)

%E Formula edited by _Robert Israel_, Jun 22 2015