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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 21 04:10 EDT 2021. Contains 345354 sequences. (Running on oeis4.)