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 A176303 a(n) = abs(2^n-127). 5
 126, 125, 123, 119, 111, 95, 63, 1, 129, 385, 897, 1921, 3969, 8065, 16257, 32641, 65409, 130945, 262017, 524161, 1048449, 2097025, 4194177, 8388481, 16777089, 33554305, 67108737, 134217601, 268435329, 536870785, 1073741697, 2147483521, 4294967169 (list; graph; refs; listen; history; text; internal format)
 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 *) 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 See A175347, A169716 for primes. Sequence in context: A267342 A278935 A267395 * A157321 A100730 A044876 Adjacent sequences:  A176300 A176301 A176302 * A176304 A176305 A176306 KEYWORD nonn,easy AUTHOR Vladimir Shevelev, Apr 14 2010 STATUS approved

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