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A232821
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a(n) = n^(n-1) - Sum_{k=1..n-1} k^(k-1).
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1
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1, 1, 6, 52, 549, 7075, 109172, 1971026, 40823443, 954730001, 24892154602, 716025676088, 22528094057193, 769646697066375, 28375143175948712, 1122910795732014438, 47478259662185188967, 2136067435649547983973, 101891594614083396452878
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listen;
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OFFSET
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1,3
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LINKS
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FORMULA
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EXAMPLE
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6^5 - 5^4 - 4^3 - 3^2 - 2^1 - 1^0 = 7075 so a(6) = 7075.
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MATHEMATICA
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a[n_] := n^(n - 1) - Sum[i^(i - 1), {i, 1, n - 1}]; Table[a[n], {n, 20}] (* Carlos Eduardo Olivieri, May 29 2015 *)
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PROG
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(Python)
def sub(n):
..num = n**(n-1)
..for i in range(0, n-1):
......num -= (i+1)**i
..return num
n = 1
while n < 100:
..print(sub(n), end=', ')
..n += 1
(PARI) vector(20, n, n^(n-1)-sum(i=1, n-1, i^(i-1))) \\ Derek Orr, Apr 05 2015
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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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EXTENSIONS
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STATUS
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approved
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