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Search: id:A161350
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| A161350 |
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Numbers with property that the digital sum times the product of the digits is a square |
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+0
1
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| 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 22, 30, 39, 40, 50, 60, 70, 80, 88, 90, 93, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 120, 123, 130, 132, 140, 144, 150, 160, 170, 180, 189, 190, 198, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 213, 220
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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93 is in the list because (9+3)x(9x3)= 12x27 = 324 = 18^2
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MAPLE
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a := proc (n) local nn, L: nn := convert(n, base, 10): L := nops(nn): if type(sqrt(add(nn[i], i = 1 .. L)*(product(nn[i], i = 1 .. L))), integer) = true then n else end if end proc: seq(a(n), n = 1 .. 220); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 27 2009]
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CROSSREFS
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Sequence in context: A032889 A009995 A038367 this_sequence A108652 A140665 A069024
Adjacent sequences: A161347 A161348 A161349 this_sequence A161351 A161352 A161353
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KEYWORD
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nonn,base
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AUTHOR
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Claudio L Meller (claudiomeller(AT)gmail.com), Jun 07 2009
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