OFFSET
0,1
REFERENCES
R. K. Guy, Unsolved problems in number theory, Vol.1, 1994, Springer-Verlag,pages 42-43.
LINKS
Indranil Ghosh, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
From Colin Barker, Feb 20 2017: (Start)
a(n) = 2^n - 127 for n>6.
a(n) = 3*a(n-1) - 2*a(n-2) for n>8.
G.f.: (126 - 253*x + 2*x^7 + 252*x^8) / ((1 - x)*(1 - 2*x)).
(End)
EXAMPLE
a(2) = abs(2^2-127) = abs(4-127) = abs(-123) = 123. - Indranil Ghosh, Feb 20 2017
MATHEMATICA
Table[Abs[2^n-127], {n, 0, 32}] (* or *) CoefficientList[Series[(126 - 253*x + 2*x^7 + 252*x^8) / ((1 - x)*(1 - 2*x)) , {x, 0, 30}], x] (* Indranil Ghosh, Feb 20 2017 *)
LinearRecurrence[{3, -2}, {126, 125, 123, 119, 111, 95, 63, 1, 129}, 40] (* Harvey P. Dale, Feb 11 2024 *)
PROG
(Python) def A176303(n): return abs(2**n-127) # Indranil Ghosh, Feb 20 2017
(PARI) Vec((126 - 253*x + 2*x^7 + 252*x^8) / ((1 - x)*(1 - 2*x)) + O(x^40)) \\ Colin Barker, Feb 20 2017
(PARI) a(n)=abs(2^n-127) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladimir Shevelev, Apr 14 2010
STATUS
approved