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A288068
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Repdigits in base 10 which are Brazilian numbers.
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1
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7, 8, 22, 33, 44, 55, 66, 77, 88, 99, 111, 222, 333, 444, 555, 666, 777, 888, 999, 1111, 2222, 3333, 4444, 5555, 6666, 7777, 8888, 9999, 11111, 22222, 33333, 44444, 55555, 66666, 77777, 88888, 99999, 111111, 222222, 333333, 444444, 555555, 666666, 777777, 888888, 999999
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OFFSET
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1,1
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COMMENTS
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These numbers are all repdigits belonging to A010785. The representation of the numbers 7 and 8 in base 10 is not Brazilian but they are yet Brazilian because 7 = 111_2 and 8 = 22_3. Except the repdigits 7, 8, 22, 33, 55, 77 and the primes repunits R_n from A004022 and A004023, all these Brazilian repdigits are also Brazilian in another base.
Contains all base-10 repdigits (A010785) >= 22, because these are Brazilian numbers in base 10. - R. J. Mathar, Jul 19 2024
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LINKS
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EXAMPLE
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7 = 111_2;
44 = 44_10 = 22_21;
66 = 66_10 = 33_21 = 22_32.
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MAPLE
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# reuses code of A125134, b-file output
n := 1 :
for ndigs from 1 do
for d from 1 to 9 do
r := add(d*10^i, i=0..ndigs-1) ; # rep digit d in base 10
if isA125134(r) then
printf("%d %d\n", n, r) ;
n := n+1 ;
end if;
end do:
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MATHEMATICA
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Select[Flatten@ Table[FromDigits@ ConstantArray[k, n], {n, 6}, {k, 9}], Function[n, Length@ SelectFirst[Range[2, n - 2], Count[DigitCount[n, #], _?(# > 0 &)] == 1 &] == 0]] (* Michael De Vlieger, Jun 06 2017, Version 10 *)
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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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