login
A175772
Expansion of 1/(1 - x - x^9 - x^17 + x^18).
23
1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 16, 20, 25, 31, 38, 46, 55, 67, 81, 98, 119, 145, 177, 216, 263, 320, 389, 473, 575, 699, 850, 1034, 1258, 1530, 1862, 2265, 2755, 3351, 4076, 4958, 6031, 7336, 8923, 10854, 13203, 16060, 19535, 23762
OFFSET
0,10
COMMENTS
The ratio a(n+1)/a(n) is 1.216391661138265... as n->infinity.
LINKS
Michael Mossinghoff, Small Salem Numbers
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,-1).
FORMULA
G.f.: 1/((1 - x^2 + x^4)*(1 - x^4 - x^5 - x^6 + x^10)*(1 - x + x^2 - x^3 + x^4)).
a(n) = a(n-1) + a(n-9) + a(n-17) - a(n-18). - Harvey P. Dale, Jul 13 2014
MATHEMATICA
CoefficientList[Series[1/(1 - x - x^9 - x^17 + x^18), {x, 0, 50}], x] (* or *)
LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, -1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11} , 60] (* Harvey P. Dale, Jul 13 2014 *)
PROG
(PARI) x='x+O('x^50); Vec(1/(1-x-x^9-x^17+x^18)) \\ G. C. Greubel, Nov 03 2018
(Magma) m:=50; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x-x^9-x^17+x^18))); // G. C. Greubel, Nov 03 2018
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula, Dec 04 2010
STATUS
approved