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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Lars Blomberg, Table of n, a(n) for n = 1..10000

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

Cf. A279420-A279423, A279425-A279429.

Sequence in context: A034049 A271361 A304813 * A073041 A284595 A053898

Adjacent sequences:  A279421 A279422 A279423 * A279425 A279426 A279427

KEYWORD

nonn,base,easy

AUTHOR

Lars Blomberg, Dec 22 2016

STATUS

approved

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Last modified June 15 08:52 EDT 2021. Contains 345048 sequences. (Running on oeis4.)