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A074732
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a(n+3) = floor( ( a(n) + 2*a(n+1) + 3*a(n+2) )/4 ), with a(0), a(1), a(2) equal to 0, 1, 2.
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2
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0, 1, 2, 2, 2, 3, 3, 4, 5, 6, 8, 10, 13, 16, 21, 27, 34, 44, 56, 72, 93, 119, 153, 197, 254, 327, 421, 542, 698, 899, 1158, 1492, 1922, 2477, 3191, 4112, 5298, 6827, 8797, 11335, 14606, 18821, 24252, 31251, 40269, 51890, 66864, 86160, 111024, 143064, 184350
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OFFSET
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0,3
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COMMENTS
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Ratio of each term to the previous approaches 1.28858..., a root of -4*x^3 + 3*x^2 + 2*x + 1.
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LINKS
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EXAMPLE
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a(4) = 2 because ( 1 + 2*2 + 3*2 )/4 = 2.75 and 2.75 floored = 2
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MATHEMATICA
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RecurrenceTable[{a[0]==0, a[1]==1, a[2]==2, a[n]==Floor[(a[n-3]+2a[n-2]+ 3a[n-1])/4]}, a, {n, 50}] (* Harvey P. Dale, May 14 2014 *)
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PROG
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(PARI) seq(n)={my(a=vector(n+1)); a[1]=0; a[2]=1; a[3]=2; for(n=1, #a-3, a[n+3] = (a[n] + 2*a[n+1] + 3*a[n+2])\4); a} \\ Andrew Howroyd, Feb 12 2020
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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