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A256601 Numbers n such that the decimal expansions of both n and n^2 have 1 as smallest digit and 9 as largest digit. 13
139, 219, 519, 591, 719, 891, 911, 961, 971, 981, 1139, 1193, 1219, 1292, 1293, 1296, 1319, 1339, 1389, 1391, 1392, 1394, 1396, 1469, 1579, 1589, 1691, 1719, 1729, 1769, 1793, 1839, 1869, 1896, 1911, 1927, 1937, 1939, 1944, 1946, 1969, 1978, 1979, 1981, 1986 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

fQ[n_] := Block[{d = DigitCount@ n}, Last@ d == 0 && d[[1]] > 0 && d[[9]] > 0]; Select[Range@ 2000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, Apr 20 2015 *)

PROG

(PARI) is(n) = vecmin(digits(n))==1 && vecmin(digits(n^2))==1 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9

CROSSREFS

Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197,  A257210, A257211.

Sequence in context: A027867 A140019 A107206 * A142314 A142396 A268858

Adjacent sequences:  A256598 A256599 A256600 * A256602 A256603 A256604

KEYWORD

nonn,base

AUTHOR

Felix Fröhlich, Apr 20 2015

STATUS

approved

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Last modified June 25 12:36 EDT 2019. Contains 324352 sequences. (Running on oeis4.)