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Search: id:A007603
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| A007603 |
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Power-sum numbers: let n = a_1 a_2 ... a_k be a k-digit number; n is a power-sum number if there are exponents e_1 ... e_m such that n = Sum_{i=1..m} Sum_{j=1..k} a_j^e_i.
(Formerly M0480)
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+0
1
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| 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 20, 21, 23, 24, 27, 30, 36, 40, 42, 45, 48, 50, 54, 60, 63, 70, 72, 80, 81, 84, 90, 100, 102, 104, 108, 110, 111, 112, 113, 114, 115, 116, 117, 120, 122, 126, 130, 131, 132, 133, 134, 135, 136, 140, 144, 150, 151, 152, 153, 154, 156, 160, 162, 170, 171, 172, 173, 174, 178, 180, 182
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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M. Keith, Power-sum numbers, J. Rec. Math., 18 (No. 4, 1986), 275-278.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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EXAMPLE
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21 = (2+1)+(2^3+1^3)+(2^3+1^3), with e_1, e_2, e_3 = 1, 3, 3.
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CROSSREFS
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Sequence in context: A059765 A143289 A064807 this_sequence A005349 A085135 A085133
Adjacent sequences: A007600 A007601 A007602 this_sequence A007604 A007605 A007606
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com), Mira Bernstein (mira(AT)math.berkeley.edu)
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EXTENSIONS
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Corrected and extended by Naohiro Nomoto (6284968128(AT)geocities.co.jp), Mar 11 2001
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