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A005684 Number of Twopins positions.
(Formerly M1019)
1
1, 2, 4, 6, 11, 18, 32, 52, 88, 142, 236, 382, 629, 1018, 1664, 2692, 4383, 7092, 11520, 18640, 30232, 48916, 79264, 128252, 207705, 336074, 544084 (list; graph; refs; listen; history; internal format)
OFFSET

6,2

REFERENCES

R. K. Guy, ``Anyone for Twopins?,'' in D. A. Klarner, editor, The Mathematical Gardner. Prindle, Weber and Schmidt, Boston, 1981, pp. 2-15.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

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.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

FORMULA

G.f.: x^6/(1-2x+2x^3-3x^4+2x^5+x^8). - R. Stephan, Apr 21 2004

MAPLE

A005684:=1/(z**2-z+1)/(z**2+z-1)/(z**4+z**2-1); [S. Plouffe in his 1992 dissertation.]

CROSSREFS

Sequence in context: A168445 A185192 A007053 * A018167 A140443 A115992

Adjacent sequences:  A005681 A005682 A005683 * A005685 A005686 A005687

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified February 16 12:15 EST 2012. Contains 205909 sequences.