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A279424
Numbers k such that k^2 has an odd number of digits and the middle digit is 4.
3
2, 12, 21, 29, 102, 107, 116, 120, 132, 136, 143, 153, 180, 183, 191, 196, 201, 206, 220, 229, 271, 280, 294, 299, 304, 309, 1002, 1007, 1012, 1017, 1022, 1027, 1046, 1051, 1065, 1070, 1079, 1093, 1102, 1111, 1120, 1129, 1142, 1151, 1155, 1164, 1168, 1181
OFFSET
1,1
LINKS
EXAMPLE
2^2 = (4), 136^2 = 18(4)96, 1017^2 = 103(4)289.
MATHEMATICA
Select[Range[1200], OddQ[IntegerLength[#^2]]&&IntegerDigits[#^2][[(IntegerLength[ #^2]+1)/2]]==4&] (* Harvey P. Dale, Jun 05 2017 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Lars Blomberg, Dec 22 2016
STATUS
approved