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A117746
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Numbers of the form n^2-n-1 for which the sum of the digits is also a number of the form n^2-n-1.
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0
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1, 5, 29, 41, 131, 155, 209, 379, 461, 551, 649, 991, 1055, 1121, 1189, 1639, 1721, 1891, 2351, 2449, 2755, 3079, 3305, 3781, 4159, 4421, 4555, 5699, 5851, 6005, 6319, 6805, 7309, 7831, 8371, 9505, 10099, 10301, 10505, 12431, 12655, 13339, 14761
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| 5699 is in the sequence because (1)5699=76^2-76-1, (2)the sum of its digits is 5+6+9+9=29 and (3)29 can be written as 6^2-6-1
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MATHEMATICA
| nset=Table[n^2-n-1, {n, 200}];
Rest[Select[nset, MemberQ[nset, Total[IntegerDigits[#]]]&]] [From Harvey P. Dale, Jan. 22, 2011]
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CROSSREFS
| Sequence in context: A033205 A167742 A107151 * A156053 A081116 A192090
Adjacent sequences: A117743 A117744 A117745 * A117747 A117748 A117749
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KEYWORD
| base,nonn
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AUTHOR
| Luc Stevens (lms022(AT)yahoo.com), Apr 14 2006
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