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A227221
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Volume of Johnson square pyramid placed upright on cube (rounded down) with edge lengths equal to n.
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1
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1, 9, 33, 79, 154, 266, 423, 632, 900, 1235, 1644, 2135, 2714, 3390, 4170, 5061, 6071, 7206, 8475, 9885, 11443, 13157, 15034, 17082, 19307, 21718, 24322, 27126, 30137, 33363, 36812, 40491, 44407, 48568, 52980, 57652, 62592, 67805, 73300, 79084, 85165, 91550, 98246
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OFFSET
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1,2
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COMMENTS
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Johnson square pyramid: a square base with four equilateral triangle- faces. It is placed upright on top of the cube. All the edge lengths are equal.
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LINKS
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EXAMPLE
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a(4) = 79: volume = sqrt(2)/6*k^3 + k^3 = sqrt(2)/6*4^3 + 4^3 = 79.0849446... and floor(79.0849446...) = 79.
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MAPLE
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KD:= proc() local a, b; a:=evalf(sqrt(2))/6*k^3 + k^3; b:=floor(a); RETURN(b): end: seq(KD(), k=1..100);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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