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A262067
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a(n) = n^n - (n-2)^n.
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2
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2, 4, 26, 240, 2882, 42560, 745418, 15097600, 347066882, 8926258176, 253930611002, 7916100448256, 268352394448322, 9828088361009152, 386707997366768618, 16268790735900180480, 728714136550643404802, 34624041592426892361728
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OFFSET
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1,1
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COMMENTS
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Inspired by multi-dimensional cubes: For n>1, the number of lattice points on the surface of a k-dimensional cube with side-length n is f(n,k) = n^k - (n-2)^k. a(n) = f(n,n).
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LINKS
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FORMULA
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EXAMPLE
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For n = 2, a(n) = n^n - (n-2)^n = 2^2 - (2-2)^2 = 4.
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MAPLE
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MATHEMATICA
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PROG
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(PARI) a(n) = n^n - (n-2)^n;
vector(40, n, a(n))
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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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