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A256631
Numbers n such that the decimal expansions of both n and n^2 have 0 as smallest digit and 5 as largest digit.
24
50, 105, 150, 205, 350, 450, 500, 501, 502, 505, 550, 1005, 1015, 1050, 1055, 1105, 1150, 1205, 1450, 1500, 1501, 1550, 2005, 2050, 2055, 2105, 2305, 2350, 3350, 3500, 4500, 5000, 5001, 5002, 5005, 5010, 5011, 5012, 5015, 5020, 5021, 5032, 5045, 5050, 5055
OFFSET
1,1
LINKS
MATHEMATICA
fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {6, 9}] == 0, c[[5]] > 0, c[[10]] > 0]]; Select[Range@ 5100, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, Apr 12 2015 *)
Select[Range[5100], Min[IntegerDigits[#]]==0&&Max[IntegerDigits[#] ]== 5 && Min[IntegerDigits[#^2]]==0&&Max[IntegerDigits[#^2]]==5&] (* Harvey P. Dale, Jan 19 2020 *)
PROG
(PARI) is(n) = vecmin(digits(n))==0 && vecmin(digits(n^2))==0 && vecmax(digits(n))==5 && vecmax(digits(n^2))==5
KEYWORD
nonn,base
AUTHOR
Felix Fröhlich, Apr 05 2015
STATUS
approved