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A353930
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Smallest number whose binary expansion has n distinct run-sums.
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7
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1, 2, 11, 183, 5871, 375775, 48099263, 12313411455, 6304466665215, 6455773865180671, 13221424875890015231, 54154956291645502388223, 443637401941159955564326911, 7268555193403964711965932118015, 238176016577461115681699663643131903, 15609103422420491677315869156516292427775
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OFFSET
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1,2
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COMMENTS
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Every sequence can be uniquely split into a sequence of non-overlapping runs. For example, the runs of (2,2,1,1,1,3,2,2) are ((2,2),(1,1,1),(3),(2,2)), with sums (4,3,3,4).
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LINKS
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EXAMPLE
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The terms, binary expansions, and standard compositions begin:
1: 1 (1)
2: 10 (2)
11: 1011 (2,1,1)
183: 10110111 (2,1,2,1,1,1)
5871: 1011011101111 (2,1,2,1,1,2,1,1,1,1)
375775: 1011011101111011111 (2,1,2,1,1,2,1,1,1,2,1,1,1,1,1)
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MATHEMATICA
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qe=Table[Length[Union[Total/@Split[IntegerDigits[n, 2]]]], {n, 1, 10000}];
Table[Position[qe, i][[1, 1]], {i, Max@@qe}]
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PROG
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(PARI) a(n) = {my(t=1); if(n==2, t<<=1, for(k=3, n, t = (t<<k) + (2^(k-1)-1))); t} \\ Andrew Howroyd, Jan 01 2023
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CROSSREFS
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For prime indices instead of binary expansion we have A006939.
For lengths instead of sums of runs we have A165933 = firsts in A165413.
Numbers whose binary expansion has all distinct runs are A175413.
These are the positions of first appearances in A353929.
A005811 counts runs in binary expansion.
A242882 counts compositions with distinct multiplicities.
A318928 gives runs-resistance of binary expansion.
A351014 counts distinct runs in standard compositions.
A353864 counts rucksack partitions.
Cf. A044813, A073093, A181819, A304442, A353743, A353840, A353841, A353842, A353847, A353848, A353850, A353853, A353932, A354582.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Offset corrected and terms a(7) and beyond from Andrew Howroyd, Jan 01 2023
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STATUS
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approved
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