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 A133455 a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3). 0
 4, 2, 1, 5, 16, 35, 67, 128, 253, 509, 1024, 2051, 4099, 8192, 16381, 32765, 65536, 131075, 262147, 524288, 1048573, 2097149, 4194304, 8388611, 16777219, 33554432, 67108861, 134217725, 268435456, 536870915, 1073741827, 2147483648, 4294967293, 8589934589, 17179869184 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Sequence is identical to its third differences. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,2). FORMULA a(n)-2^n = hexaperiodic 3, 0, -3, -3, 0, 3. O.g.f: -(4 - 10*x + 7*x^2)/((2*x - 1)*(x^2 - x + 1)). - R. J. Mathar, Nov 30 2007 a(n) = 2^n + 3*A010892(n+1). - R. J. Mathar, Jul 20 2009 a(n) = (-1)^n*A146321(n + 1). - Andrew Howroyd, Jan 03 2020 MATHEMATICA LinearRecurrence[{3, -3, 2}, {4, 2, 1}, 15] (* Ray Chandler, Sep 23 2015 *) PROG (PARI) Vec((4 - 10*x + 7*x^2)/((1 - 2*x)*(1 - x + x^2)) + O(x^40)) \\ Andrew Howroyd, Jan 03 2020 (MAGMA) a:=[4, 2, 1]; [n le 3 select a[n] else 3*Self(n-1) -3*Self(n-2)+2*Self(n-3):n in [1..35]]; // Marius A. Burtea, Jan 03 2020 (MAGMA) R:=PowerSeriesRing(Integers(), 35); Coefficients(R!( (4 - 10*x + 7*x^2)/((1 - 2*x)*(1 - x + x^2)))); // Marius A. Burtea, Jan 03 2020 CROSSREFS Cf. A010892, A146321. Sequence in context: A016506 A228132 A146321 * A122606 A277744 A119953 Adjacent sequences:  A133452 A133453 A133454 * A133456 A133457 A133458 KEYWORD nonn AUTHOR Paul Curtz, Nov 27 2007 EXTENSIONS Terms a(15) and beyond from Andrew Howroyd, Jan 03 2020 STATUS approved

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Last modified June 25 10:09 EDT 2021. Contains 345453 sequences. (Running on oeis4.)