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A273364 Numbers n such that the decimal number concat(9,n) is a square. 8
61, 216, 409, 604, 801, 1204, 1809, 2416, 3025, 3636, 4249, 4864, 5481, 6100, 6721, 7344, 7969, 8596, 9225, 9856, 10116, 12025, 13936, 15849, 17764, 19681, 21600, 23521, 25444, 27369, 29296, 31225, 33156, 35089, 37024, 38961, 40900, 42841, 44784 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Elements are squares of integers in (sqrt(91), 10) * sqrt(10)^k without the leading 9 elements for nonnegative k. - David A. Corneth, May 20 2016
LINKS
EXAMPLE
61 is a member because 961 = 31^2 is a square.
0 is not a member because 90 is not a square.
MAPLE
t1:=[];
for k from 1 to 50000 do
if issqr(k+9*10^length(k)) then t1:=[op(t1), k]; fi;
od;
t1;
MATHEMATICA
Select[Range[45000], IntegerQ[Sqrt[9*10^IntegerLength[#]+#]]&] (* Harvey P. Dale, Feb 19 2020 *)
PROG
(Magma) [n: n in [1..50000 ] | IsSquare(Seqint(Intseq(n) cat Intseq(9)))]; // Vincenzo Librandi, Feb 20 2020
CROSSREFS
Sequence in context: A234925 A171585 A038643 * A297731 A228130 A142267
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified February 26 16:21 EST 2024. Contains 370352 sequences. (Running on oeis4.)