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Search: id:A077759
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| A077759 |
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Smaller of the two successive triangular numbers which differ in the use of only one digit. |
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+0
1
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| 0, 1, 3, 10, 15, 21, 45, 105, 136, 190, 210, 231, 325, 435, 465, 780, 1081, 1225, 1485, 1596, 2415, 3081, 4005, 4465, 4560, 5253, 6670, 7021, 7750, 9730, 14365, 15576, 16653, 17020, 19306, 20100, 20301, 23436, 24310, 24531, 30135, 30628, 36585
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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The ith triangular number T(i) is in the sequence if and only if its successor T(i+1) can be obtained by changing a single digit of T(i) and, if necessary, changing the order of the digits. Thus the sequence does not include 55, even though it and its successor 66 could be said to "differ in the use of only one digit" (i.e., using 5 vs. using 6). Triangular numbers such as 404550, whose successor 405450 uses the same digits in the same frequencies, would also be excluded. [From Jon E. Schoenfield (jonscho(AT)hiwaay.net), Sep 05 2009]
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EXAMPLE
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231 belongs to this sequence as 231 and 253 differ in the use of only one digit i.e. 1 and 5.
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CROSSREFS
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Sequence in context: A108770 A112355 A074314 this_sequence A063231 A030005 A129307
Adjacent sequences: A077756 A077757 A077758 this_sequence A077760 A077761 A077762
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 21 2002
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EXTENSIONS
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More terms from Jon E. Schoenfield (jonscho(AT)hiwaay.net), Sep 05 2009
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