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A359453
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Number of vertices in the partite set of the n-Menger sponge graph that do not contain the corners.
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10
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0, 12, 192, 4032, 79872, 1600512, 31997952, 640008192, 12799967232, 256000131072, 5119999475712, 102400002097152, 2047999991611392, 40960000033554432, 819199999865782272, 16384000000536870912, 327679999997852516352, 6553600000008589934592, 131071999999965640261632
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OFFSET
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0,2
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COMMENTS
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This sequence and the sequence counting the corner vertices (A359452) alternate as to which is larger.
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LINKS
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FORMULA
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a(n) = (20^n - (-4)^n)/2.
O.g.f.: 12*x/((1 - 20*x)*(1 + 4*x)).
E.g.f.: (cosh(8*x) + sinh(8*x))*sinh(12*x). (End)
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EXAMPLE
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The level 1 Menger sponge graph can be formed by subdividing every edge of a cube graph. This produces a graph with 8 corner vertices and 12 non-corner vertices, so a(1) = 12.
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MATHEMATICA
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PROG
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(Python)
def A359453(n): return (10**n<<n-1)+(1<<(n<<1)-1 if n&1 else -(1<<(n<<1)-1)) if n else 0 # Chai Wah Wu, Feb 13 2023
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CROSSREFS
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Cf. A359452 (number of corner vertices).
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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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