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 A034189 Number of binary codes of length 4 with n words. 12
 1, 1, 4, 6, 19, 27, 50, 56, 74, 56, 50, 27, 19, 6, 4, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Also number of 2-colorings of the vertices of the 4-cube having n nodes of one color. REFERENCES W. Y. C. Chen, Induced cycle structures of the hyperoctahedral group. SIAM J. Disc. Math. 6 (1993), 353-362. H. Fripertinger, Enumeration, construction and random generation of block codes, Designs, Codes, Crypt., 14 (1998), 213-219. R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1979. LINKS Table of n, a(n) for n=0..16. H. Fripertinger, Isometry Classes of Codes MATHEMATICA (* From Robert A. Russell, May 08 2007: (Start) *) P[ n_Integer ]:=P[ n ]=P[ n, n ]; P[ n_Integer, _ ]:={}/; (n<0); (* partitions *) P[ 0, _ ]:={{}}; P[ n_Integer, 1 ]:={Table[ 1, {n} ]}; P[ _, 0 ]:={}; (*S.S. Skiena*) P[ n_Integer, m_Integer ]:=Join[ Map[ (Prepend[ #, m ])&, P[ n-m, m ] ], P[ n, m-1 ] ]; AC[ d_Integer ]:=Module[ {C, M, p}, (* from W.Y.C. Chen algorithm *) M[ p_List ]:=Plus@@p!/(Times@@p Times@@(Length/@Split[ p ]!)); C[ p_List, q_List ]:=Module[ {r, m, k, x}, r=If[ 0==Length[ q ], 1, 2 2^ IntegerExponent[ LCM@@q, 2 ] ]; m=LCM@@Join[ p/GCD[ r, p ], q/GCD[ r, q ] ]; CoefficientList[ Expand[ Product[ (1+x^(k r))^((Plus@@Map[ MoebiusMu[ k/# ] 2^Plus@@GCD[# r, Join[ p, q ] ]&, Divisors[ k ] ])/(k r)), {k, 1, m} ] ], x ] ]; Sum[ Binomial[ d, p ]Plus@@Plus@@Outer[ M[ #1 ]M[ #2 ]C[ #1, #2 ]2^(d-Length[ #1 ]-Length[ #2 ])&, P[ p ], P[ d-p ], 1 ], {p, 0, d} ]/(d!2^d) ]; AC[ 4 ] (* End *) CROSSREFS Cf. A034188, A034190, A034191, A034192, A034193, A034194, A034195, A034196, A034197. Cf. A171872 and A171876. - Robert Munafo, Jan 25 2010 A row of A039754. Sequence in context: A012928 A013160 A153777 * A024697 A024874 A095383 Adjacent sequences: A034186 A034187 A034188 * A034190 A034191 A034192 KEYWORD nonn,fini,full AUTHOR N. J. A. Sloane EXTENSIONS Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, May 11 2007 STATUS approved

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Last modified September 28 19:19 EDT 2023. Contains 365737 sequences. (Running on oeis4.)