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 A087288 a(n)=2a(n-1)+a(n-2)-2a(n-3). 5
 4, 4, 10, 16, 34, 64, 130, 256, 514, 1024, 2050, 4096, 8194, 16384, 32770, 65536, 131074, 262144, 524290, 1048576, 2097154, 4194304, 8388610, 16777216, 33554434, 67108864, 134217730, 268435456, 536870914, 1073741824, 2147483650 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS a(n)=(A000051(n)-A014551(n))/2. LINKS Indranil Ghosh, Table of n, a(n) for n = 0..3314 Index entries for linear recurrences with constant coefficients, signature (2,1,-2). FORMULA G.f.: (4-4x-2x^2)/(1-2x-x^2+2x^3). a(n)=2^(n+1)+1+(-1)^n. MATHEMATICA CoefficientList[Series[(4 - 4x - 2x^2)/(1 - 2x - x^2 + 2x^3), {x, 0, 30}], x] PROG (PARI) a(n)=2<

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Last modified January 24 04:35 EST 2020. Contains 331183 sequences. (Running on oeis4.)