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A363706
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a(n) is the sigma irregularity of the n-th power of a path graph of length at least 3*n.
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0
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2, 14, 52, 140, 310, 602, 1064, 1752, 2730, 4070, 5852, 8164, 11102, 14770, 19280, 24752, 31314, 39102, 48260, 58940, 71302, 85514, 101752, 120200, 141050, 164502, 190764, 220052, 252590, 288610, 328352, 372064, 420002, 472430, 529620, 591852, 659414, 732602, 811720, 897080, 989002
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OFFSET
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1,1
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COMMENTS
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The sigma irregularity of a graph is the sum of the squares of the differences between the degrees over all edges of the graph.
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LINKS
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FORMULA
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a(n) = (n^4 + 2*n^3 + 2*n^2 + n)/3.
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EXAMPLE
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A path of length at least 3 has two edges between vertices with degrees 1 and 2. Thus a(1) = 2.
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MATHEMATICA
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Table[(n^4 + 2*n^3 + 2*n^2 + n)/3, {n, 1, 40}] (* Amiram Eldar, Jul 28 2023 *)
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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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