This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A132105 Number of distinct Tsuro tiles which are n-gonal in shape and have 2 points per side. 6
 1, 1, 3, 7, 30, 137, 1065, 10307, 130040, 1927853, 32809979, 625303343, 13178378742, 304081128617, 7623562484349, 206343110670031, 5996839161108904, 186254714746749377, 6156752738537004317, 215810382975655205399, 7995774673152799224930 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Turning over is allowed. See A132100 for definition and comments. LINKS MAPLE # B(n, m) gives the number of n-sided tiles with m points per side, allowing reflections (cf. comments and formula of A132100) with(numtheory): a:=(p, r)->piecewise(p mod 2 = 1, p^(r/2)*doublefactorial(r-1), sum(p^j*binomial(r, 2*j)*doublefactorial(2*j - 1), j = 0 .. floor(r/2))); B := (n, m)->piecewise(n*m mod 2=1, 0, add(phi(p)*a(p, m*n/p), p in divisors(n))/(2*n)+ piecewise(m mod 2=0, a(2, m*n/2)*2, a(2, m*n/2)+a(2, m*n/2-1))/4); A132105 := n -> B(n, 2); [seq(A132105(n), n=1..20)]; # Laurent Tournier, Jul 09 2014 CROSSREFS Cf. A132100-A132104, A007769, A001147, A054499. Sequence in context: A277739 A098644 A182322 * A019021 A110505 A009128 Adjacent sequences:  A132102 A132103 A132104 * A132106 A132107 A132108 KEYWORD nonn AUTHOR Keith F. Lynch, Oct 31 2007 EXTENSIONS More terms from Laurent Tournier, Jul 09 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 17 08:17 EST 2018. Contains 317275 sequences. (Running on oeis4.)