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Search: id:A060946
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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 <= i <= n, 0 <= j <= n-1. |
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3
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| 1, 3, 12, 76, 701, 8477, 126126, 2223278, 45269999, 1045269999, 26982694600, 769991065288, 24068076187769, 817782849441913, 30010708874832538
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OFFSET
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1,2
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COMMENT
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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 (ctibor.zizka(AT)seznam.cz), Feb 23 2008
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LINKS
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C. P. Simoes, Teste de Desempenho Mental.
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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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MATHEMATICA
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Table[Sum[i^(i-1), {i, n}], {n, 15}]
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CROSSREFS
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A000178, A001923.
Cf. A000169.
Sequence in context: A134524 A120591 A032114 this_sequence A121421 A136735 A108043
Adjacent sequences: A060943 A060944 A060945 this_sequence A060947 A060948 A060949
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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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More terms from Zak Seidov (zakseidov(AT)yahoo.com), Jul 07 2003
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