A257485 Numbers n such that the decimal expansions of both n and n^2 have 2 as smallest digit and 9 as largest digit.

927, 962, 982, 2293, 2393, 2593, 2693, 2792, 2923, 2927, 2932, 2937, 2964, 2973, 2977, 2982, 2983, 4792, 4923, 4927, 5692, 6292, 6923, 6925, 6927, 7923, 7924, 7927, 8792, 8925, 9232, 9233, 9267, 9268, 9273, 9286, 9287, 9288, 9325, 9326, 9327, 9342, 9423, 9427

Offset: 1

Author

Felix Fröhlich, Apr 26 2015

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257123, A257368.

Programs

Mathematica

fQ[n_] := Block[{d = DigitCount@ n}, Plus @@ Join[First@ d, Last@ d] == 0 && d[[2]] > 0 && d[[9]] > 0]; Select[Range@ 10000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, Apr 27 2015 *)
s2l9Q[n_]:=Max[IntegerDigits[n]]==9&&Min[IntegerDigits[n]]==2; Select[ Range[ 10000],AllTrue[{#,#^2},s2l9Q]&] (* Harvey P. Dale, Dec 06 2018 *)

PARI

is(n) = vecmin(digits(n))==2 && vecmin(digits(n^2))==2 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9