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 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 Robert Israel, Table of n, a(n) for n = 7..10000 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 Adjacent sequences: A030504 A030505 A030506 * A030508 A030509 A030510 KEYWORD nonn AUTHOR Mattias Svanstrom (mattias(AT)isy.liu.se) EXTENSIONS Formula edited by Robert Israel, Jun 22 2015 STATUS approved

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Last modified April 17 01:50 EDT 2024. Contains 371756 sequences. (Running on oeis4.)