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A173722
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Partial sums of round(n^2/8).
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3
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0, 0, 1, 2, 4, 7, 12, 18, 26, 36, 49, 64, 82, 103, 128, 156, 188, 224, 265, 310, 360, 415, 476, 542, 614, 692, 777, 868, 966, 1071, 1184, 1304, 1432, 1568, 1713, 1866, 2028, 2199, 2380, 2570, 2770, 2980, 3201, 3432, 3674, 3927, 4192, 4468, 4756, 5056, 5369
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OFFSET
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0,4
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COMMENTS
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} round(k^2/8).
a(n) = round((2*n^3+3*n^2+4*n)/48).
a(n) = round((2*n+1)*(2*n^2+2*n+3)/96).
a(n) = floor((n+2)*(2*n^2-n+6)/48).
a(n) = ceiling((2*n^3+3*n^2+4*n-9)/48).
a(n) = a(n-4)+n*(n-3)/2+2, n>3.
G.f.: x^2*(1-x+x^2) / ( (1+x)*(x^2+1)*(x-1)^4 ). - R. J. Mathar, Nov 26 2010
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EXAMPLE
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a(5) = round(1/8) + round(4/8) + round(9/8) + round(16/8) + round(25/8) = 0 + 1 + 1 + 2 + 3 = 7.
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MAPLE
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A057077 := proc(n) op( 1+(n mod 4), [1, 1, -1, -1]) ; end proc:
A173722 := proc(n) 3*(-1)^n/32+n^2/16+n/12+n^3/24+1/32-A057077(n)/8 ; end proc:
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MATHEMATICA
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Table[Floor[(n + 2)*(2*n^2 - n + 6)/48], {n, 0, 50}] (* G. C. Greubel, Nov 29 2016 *)
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PROG
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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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STATUS
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approved
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