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A006060
Triangular star numbers.
(Formerly M5425)
2
1, 253, 49141, 9533161, 1849384153, 358770992581, 69599723176621, 13501987525271953, 2619315980179582321, 508133798167313698381, 98575337528478677903653, 19123107346726696199610361
OFFSET
1,2
REFERENCES
M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, p. 20.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
B. Berselli, Table of n, a(n) for n = 1..400. [From Bruno Berselli, Jul 07 2010]
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992
Eric Weisstein's World of Mathematics, Star Number
FORMULA
G.f.: (1 + 58x + x^2)/((x-1)(1 - 194x + x^2)). - Ralf Stephan, Apr 23 2004
From Bruno Berselli, Jul 07 2010: (Start)
a(n) = 194*a(n-1) - a(n-2) + 60 (n>2).
a(n) = (3*((7 + 4*sqrt(3))^(2*n-1) + (7 - 4*sqrt(3))^(2*n-1)) - 10)/32 (n>0).
(End)
MAPLE
A006060:=-(1+58*z+z**2)/(z-1)/(z**2-194*z+1); # conjectured (correctly) by Simon Plouffe in his 1992 dissertation
a:= n-> (Matrix([[253, 1, 1]]). Matrix([[195, 1, 0], [ -195, 0, 1], [1, 0, 0]])^n)[1, 3]: seq(a(n), n=1..20); # Alois P. Heinz, Aug 14 2008
MATHEMATICA
a006060 = {}; Do[
If[Length[a006060] < 2, AppendTo[a006060, 1],
AppendTo[a006060, 194*a006060[[-1]] + 60 - a006060[[-2]]]], {n,
20}]; TableForm[Transpose[List[Range[Length[a006060]], a006060]]] (* Michael De Vlieger *)
LinearRecurrence[{195, -195, 1}, {1, 253, 49141}, 20] (* Harvey P. Dale, Jan 12 2017 *)
CROSSREFS
KEYWORD
nonn
EXTENSIONS
Extended by Eric W. Weisstein, Mar 01 2002
STATUS
approved