Search: id:A000269
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%I A000269 M3014 N1220
%S A000269 3,16,67,251,888,3023,10038,32722,105228,334836,1056611,3311784,
%T A000269 10322791,32026810,98974177,304835956,936147219,2867586542,8764280567,
%U A000269 26733395986,81399821915,247459136331,751211286356,2277496842016
%N A000269 Number of trees with n nodes, 3 of which are labeled.
%D A000269 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A000269 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000269 J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 
               138.
%H A000269 T. D. Noe, <a href="b000269.txt">Table of n, a(n) for n=3..200</a>
%H A000269 <a href="Sindx_Tra.html#trees">Index entries for sequences related to 
               trees</a>
%F A000269 G.f.: A(x) = B(x)^3*(3-2*B(x))/(1-B(x))^3, where B(x) is g.f. for rooted 
               trees with n nodes, cf. A000081. - Vladeta Jovovic (vladeta(AT)eunet.rs), 
               Oct 19 2001
%F A000269 a(n) = A000524(n)-2*A000243(n).
%Y A000269 Cf. A000055, A000107, A000243, A000444, A000485, A000524-A000526.
%Y A000269 Sequence in context: A007143 A062960 A044046 this_sequence A015524 A012279 
               A037098
%Y A000269 Adjacent sequences: A000266 A000267 A000268 this_sequence A000270 A000271 
               A000272
%K A000269 nonn,easy,nice
%O A000269 3,1
%A A000269 N. J. A. Sloane (njas(AT)research.att.com).
%E A000269 More terms, new description and formula from Christian G. Bower (bowerc(AT)usa.net), 
               Nov 15 1999.

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