A279423 Numbers k such that k^2 has an odd number of digits and the middle digit is 3.
111, 124, 128, 139, 146, 156, 177, 188, 213, 231, 269, 287, 312, 1036, 1041, 1055, 1060, 1074, 1088, 1097, 1106, 1115, 1124, 1133, 1146, 1159, 1172, 1189, 1193, 1214, 1218, 1222, 1226, 1274, 1278, 1282, 1286, 1305, 1309, 1313, 1328, 1343, 1354, 1365, 1376
Offset: 1
Examples
111^2 = 12(3)21, 231^2 = 53(3)61, 1214^2 = 147(3)796.
Links
- Lars Blomberg, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
ond3Q[n_]:=Module[{idn2=IntegerDigits[n^2],len},len=Length[idn2];OddQ[ len] && idn2[[(len+1)/2]]==3]; Select[Range[1400],ond3Q] (* Harvey P. Dale, Apr 06 2018 *)