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A272615
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Numbers with digits in descending numerical order in base 2, 3 and 4 expansions.
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1
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OFFSET
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1,3
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COMMENTS
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a(10), if it exists, has more than 1000 decimal digits. Conjecture: there are no more terms in this sequence. - Charles R Greathouse IV, May 03 2016
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LINKS
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EXAMPLE
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12 is 1100 in base 2, 110 in base 3 and 30 in base 4; in each representation every digit is smaller than or equal to the one proceeding so 12 is a term.
Similarly, 63 is 111111 in base 2, 2100 in base 3 and 333 in base 4 so it is also a term.
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PROG
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(PARI) dec(n, b)=my(v=digits(n, b)); v==vecsort(v, , 4)
(PARI) dec(n, b)=my(v=digits(n, b)); v==vecsort(v, , 4)
list(lim)=my(v=List([0]), t); for(i=1, logint(lim\1+1, 4), t=4^i-1; while(t<=lim, if(dec(t, 3), listput(v, t)); t*=4); t=2*4^i-2; while(t<=lim, if(dec(t, 3), listput(v, t)); t*=4)); Set(v) \\ Charles R Greathouse IV, May 03 2016
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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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STATUS
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approved
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