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Search: id:A117511
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| A117511 |
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Triangular numbers for which the sum of the digits equals the sum of the digits of the next triangular number. |
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+0
1
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| 36, 153, 2556, 3240, 4851, 5778, 9045, 11628, 13041, 14706, 17766, 19503, 33930, 41328, 46665, 49455, 52326, 71253, 74691, 81810, 85491, 93096, 109278, 122265, 131328, 140715, 145530, 160461, 170820, 181503, 192510, 203841, 252405, 258840
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OFFSET
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1,1
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COMMENT
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s(n) stands for the sum of the digits of n. Each number of the sequence is divisible by 9.
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FORMULA
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s(a(n))=s(a(n+1))
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EXAMPLE
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153 is in the sequence because (1) 153 is triangular number a(18), triangular number a(19)=171, and (2) 1+5+3=1+7+1
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CROSSREFS
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Cf. A000217.
Sequence in context: A003848 A039495 A034592 this_sequence A064244 A064500 A017054
Adjacent sequences: A117508 A117509 A117510 this_sequence A117512 A117513 A117514
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KEYWORD
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base,nonn
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AUTHOR
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Luc Stevens (lms022(AT)yahoo.com), Apr 26 2006
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