Search: id:A094958 Results 1-1 of 1 results found. %I A094958 %S A094958 1,2,4,5,8,10,16,20,32,40,64,80,128,160,256,320,512,640,1024,1280,2048, %T A094958 2560,4096,5120,8192,10240,16384,20480,32768,40960,65536,81920,131072, %U A094958 163840,262144,327680,524288,655360,1048576,1310720,2097152 %N A094958 Numbers of the form 2^n or 5*2^n. %C A094958 The subset {a(1),...,a(2k)} together with a(2k+2) is the set of proper divisors of 5*2^k. %C A094958 Comment from Wouter Meeussen (wouter.meeussen(AT)pandora.be), Apr 10 2005: This appears to be the same sequence as "Numbers n such that n^2 is not the sum of three nonzero squares". Don Reble and Paul Pollack respond: Yes, that is correct. %C A094958 For a(n)>4: number of vertices of complete graphs that can be properly edge-colored in such a way that the edges can be partitioned into edge disjoint multicolored isomorphic spanning trees. %C A094958 Also numbers k such that k^2=a^2+b^2+c^2 has no solutions in the positive integers a, b and c. - Wouter Meeussen (wouter.meeussen(AT)pandora.be), Apr 20 2005 %H A094958 G. M. Constantine, Multicolored parallelisms of isomorphic spanning trees, Discrete Mathematics and Theoretical Computer Science, 5(2002), 121-126. %F A094958 a(1)=1, a(2)=2, a(3)=4, for n>=0, a(2n+3) = 4*2^n, a(2n+4) = 5*2^n. %F A094958 Recurrence: for n>4, a(n) = 2a(n-2). %F A094958 G.f.: [x(1+x)(1+x+x^2)]/[1-2x^2]. %Y A094958 Cf. A029744, A029745. Union of A000079 and A020714. %Y A094958 Complement of A005767. %Y A094958 Sequence in context: A133075 A018433 A115831 this_sequence A018565 A018391 A018310 %Y A094958 Adjacent sequences: A094955 A094956 A094957 this_sequence A094959 A094960 A094961 %K A094958 nonn,easy %O A094958 1,2 %A A094958 Ralf Stephan, Jun 01 2004 Search completed in 0.001 seconds