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A372281
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Numbers written in base of triangular numbers where the trailing digits are made as high as possible.
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0
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1, 2, 3, 4, 5, 6, 7, 8, 9, 17, 18, 19, 27, 28, 29, 37, 38, 39, 47, 48, 49, 57, 58, 59, 67, 68, 69, 77, 78, 79, 87, 88, 89, 97, 98, 99, 187, 188, 189, 197, 198, 199, 287, 288, 289, 297, 298, 299, 387, 388, 389, 397, 398, 399, 487, 488, 489, 497, 498, 499, 587
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OFFSET
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1,2
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COMMENTS
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This sequence differs from A000462 whose leading digits are made as high as possible.
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LINKS
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EXAMPLE
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The digits (from right to left) have values 1, 3, 6, 10, etc. (A000217), hence a(61) = 587 because 61 = 5*6 + 8*3 + 7*1.
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MATHEMATICA
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A000217[n_]:=n(n+1)/2; a[n_]:=Module[{s=0}, num=n; digits={}; s=Ceiling[Root[9(#1^3+3#1^2+2#1)-6num &, 1]]; While[s>0, AppendTo[digits, d=Ceiling[(num-9(s-1)^2)/A000217[s]]]; num-=d*A000217[s]; s--]; FromDigits[digits]]; Array[a, 61]
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CROSSREFS
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9*A000292(n) gives the number of terms with at most n digits.
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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