A257123 Numbers n such that the decimal expansions of both n and n^2 have 2 as smallest digit and 7 as largest digit.

275, 2574, 2725, 2765, 4762, 5725, 6762, 7244, 7262, 23765, 25744, 27244, 27325, 27434, 27465, 27525, 27632, 27665, 47725, 52275, 52376, 52475, 52576, 52675, 57242, 67426, 72266, 72275, 72424, 72426, 72576, 72624, 73325, 73725, 74326, 75725, 233725, 233744

Offset

1,1

Links

Felix Fröhlich, Table of n, a(n) for n = 1..1000

Mathematica

sd2Q[n_]:=With[{c=IntegerDigits[n]}, Min[c]==2&&Max[c]==7]; Select[Range[240000], AllTrue[{#, #^2}, sd2Q]&] (* Harvey P. Dale, Jan 06 2026 *)

Prog

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

Crossrefs

Cf. A137094, A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257368, A257485, A257486, A257498, A257534.

Sequence in context: A063368 A028531 A028533 * A130292 A133536 A224109

Adjacent sequences: A257120 A257121 A257122 * A257124 A257125 A257126

Keyword

nonn,base

Author

Felix Fröhlich, Apr 25 2015

Status

approved