The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 Nathan Fox, Table of n, a(n) for n = 1..10000 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 Cf. A272671, A273357, A273358, A273359, A273360, A273361, A273362, A273363. Sequence in context: A234925 A171585 A038643 * A297731 A228130 A142267 Adjacent sequences: A273361 A273362 A273363 * A273365 A273366 A273367 KEYWORD nonn,base AUTHOR Nathan Fox, Brooke Logan, and N. J. A. Sloane, May 20 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

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