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A060946
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Trace of Vandermonde matrix of numbers 1,2,...,n, i.e., the matrix A with A[i,j] = i^(j-1), 1 <= i <= n, 1 <= j <= n.
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10
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1, 3, 12, 76, 701, 8477, 126126, 2223278, 45269999, 1045269999, 26982694600, 769991065288, 24068076187769, 817782849441913, 30010708874832538, 1182932213481679514, 49844124089148547995, 2235755683827845079963, 106363105981739086612804
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OFFSET
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1,2
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COMMENTS
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A member of the family of sequences defined by a(n) = Sum_{i=1..n}[i*c(1)*..*c(r)]^(i-1); c(i) integers. Here c(1)=1. - Ctibor O. Zizka, Feb 23 2008
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LINKS
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FORMULA
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a(n) = Sum_{k=1..n} k^(k-1).
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EXAMPLE
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a(3) = 12 because the matrix is: 1,1,1 1,2,4 1,3,9 and the trace is 1+2+9 = 12.
1 = 1^0; 3 = 1^0 + 2^1; 12 = 1^0 + 2^1 + 3^2; 76 = 1^0 + 2^1 + 3^2 + 4^3.
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MAPLE
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a:=n-> sum((j+1)^j, j=0..n-1): seq(a(n), n=1..25); # Zerinvary Lajos, Dec 17 2008
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MATHEMATICA
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Table[Sum[i^(i-1), {i, n}], {n, 25}]
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PROG
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(PARI) { for (n=1, 100, write("b060946.txt", n, " ", sum(k=1, n, k^(k - 1))); ) } \\ Harry J. Smith, Jul 15 2009
(Magma) [(&+[j^(j-1): j in [1..n]]): n in [1..25]]; // G. C. Greubel, Apr 09 2021
(Sage) [sum(j^(j-1) for j in (1..n)) for n in (1..25)] # G. C. Greubel, Apr 09 2021
(Python)
from itertools import accumulate, count, islice
def A060946_gen(): # generator of terms
yield from accumulate((k**(k-1) for k in count(1)))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Ahmed Fares (ahmedfares(AT)my-deja.com), May 08 2001
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EXTENSIONS
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STATUS
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approved
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