Search: id:A005689 Results 1-1 of 1 results found. %I A005689 M1042 %S A005689 1,2,4,7,11,16,22,30,42,61,91,137,205,303,443,644,936,1365,1999,2936, %T A005689 4316,6340,9300,13625,19949,29209,42785,62701,91917,134758,197548,289547 %N A005689 Number of Twopins positions. %D A005689 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %D A005689 S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992. %D A005689 R. Austin and R. K. Guy, Binary sequences without isolated ones, Fib. Quart., 16 (1978), 84-86. %D A005689 R. K. Guy, ``Anyone for Twopins?,'' in D. A. Klarner, editor, The Mathematical Gardner. Prindle, Weber and Schmidt, Boston, 1981, pp. 2-15. %H A005689 S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992. %H A005689 S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992. %F A005689 G.f.: (1+x^2+x^3+x^4+x^5)/(1-2x+x^2-x^6). - R. Stephan, Apr 20 2004 %F A005689 Sum{k=0..floor(n/6), binomial(n-4k, 2k)} is 1, 1, 1, 1, 1, 1, 2, 4, 7, 11, ... - Paul Barry (pbarry(AT)wit.ie), Sep 16 2004 %p A005689 A005689:=-(1+z**2+z**3+z**4+z**5)/(z**3+z-1)/(z**3-z+1); [Conjectured by S. Plouffe in his 1992 dissertation.] %Y A005689 Sequence in context: A000124 A152947 A098574 this_sequence A131075 A133523 A114805 %Y A005689 Adjacent sequences: A005686 A005687 A005688 this_sequence A005690 A005691 A005692 %K A005689 nonn %O A005689 6,2 %A A005689 N. J. A. Sloane (njas(AT)research.att.com). Search completed in 0.004 seconds