login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A273360 Numbers n such that the decimal number concat(5,n) is a square. 8
29, 76, 184, 329, 476, 625, 776, 929, 1076, 1529, 1984, 2441, 2900, 3361, 3824, 4289, 4756, 5225, 5696, 6169, 6644, 7121, 7600, 8081, 8564, 9049, 9536, 11225, 12656, 14089, 15524, 16961, 18400, 19841, 21284, 22729, 24176, 25625, 27076 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Elements are squares of integers in (sqrt(51), sqrt(60)) * sqrt(10)^k without the leading 5 elements for nonnegative k. - David A. Corneth, May 20 2016

LINKS

Nathan Fox, Table of n, a(n) for n = 1..10000

EXAMPLE

76 is a member because 576 = 24^2 is a square.

0 is not a member because 50 is not a square.

MAPLE

t1:=[];

for k from 1 to 50000 do

if issqr(k+5*10^length(k)) then t1:=[op(t1), k]; fi;

od;

t1;

MATHEMATICA

Select[Range[30000], IntegerQ[Sqrt[5*10^IntegerLength[#]+#]]&] (* Harvey P. Dale, Jan 01 2019 *)

CROSSREFS

Cf. A272671, A273357, A273358, A273359, A273361, A273362, A273363, A273364.

Sequence in context: A184072 A071110 A263534 * A176185 A044167 A044548

Adjacent sequences:  A273357 A273358 A273359 * A273361 A273362 A273363

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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 20 23:22 EDT 2019. Contains 321354 sequences. (Running on oeis4.)