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A069601
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Smallest triangular number containing all the digits of numbers from 1 to n.
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1
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1, 21, 231, 12403, 24531, 235641, 2467531, 13862745, 153694278, 10429651378, 1017139458621, 101114872391625, 10111496127133528, 1011137441915312286, 101111293764315411825, 10111111491815764232356, 1011111155214617733491628, 101111111617874325294116835
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OFFSET
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1,2
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COMMENTS
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For a(10) and higher, all duplicated digits must be in the term (for example a(10) has two 1's).
Conjecture: except for a(4), the digits of a(n) are exactly all the digits of numbers from 1 to n. - Chai Wah Wu, May 18 2020
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LINKS
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EXAMPLE
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a(5) = 219453 = T(662) contains digits 1, 2, 3, 4 and 5.
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jan 24 2003
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STATUS
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approved
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