A256634 Numbers n such that the decimal expansions of both n and n^2 have 0 as smallest digit and 7 as largest digit.

740, 760, 1071, 1740, 2074, 2705, 2710, 2740, 2750, 2760, 3705, 3710, 3760, 4071, 4705, 4740, 4760, 5071, 5705, 5760, 6740, 7074, 7240, 7260, 7400, 7550, 7560, 7600, 7601, 7760, 10076, 10174, 10274, 10275, 10371, 10375, 10376, 10571, 10710, 10724, 10726, 10740

Offset

1,1

Links

Felix Fröhlich, Table of n, a(n) for n = 1..10000

Mathematica

fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {8, 9}] == 0, c[[7]] > 0, c[[10]] > 0]]; Select[Range@ 10800, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, Apr 12 2015 *)

Prog

(PARI) is(n) = vecmin(digits(n))==0 && vecmin(digits(n^2))==0 && vecmax(digits(n))==7 && vecmax(digits(n^2))==7

Crossrefs

Cf. A136813, A256630, A256631, A256633, A256708, A256709.

Sequence in context: A066404 A066402 A243778 * A105391 A319043 A044984

Adjacent sequences: A256631 A256632 A256633 * A256635 A256636 A256637

Keyword

nonn,base

Author

Felix Fröhlich, Apr 05 2015

Status

approved