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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A217570 Numbers n such that floor(sqrt(n)) = floor(n/(floor(sqrt(n))-1))-1. 3
 9, 16, 17, 25, 26, 27, 36, 37, 38, 39, 49, 50, 51, 52, 53, 64, 65, 66, 67, 68, 69, 81, 82, 83, 84, 85, 86, 87, 100, 101, 102, 103, 104, 105, 106, 107, 121, 122, 123, 124, 125, 126, 127, 128, 129, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 169, 170, 171, 172, 173 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The sequence consists of numbers n^2+k, 0<=k<=n-3, n=3,4,5,... - M. F. Hasler, Oct 09 2012 One of four sequences given by classifying natural numbers according to the value of floor(sqrt(n)). See the paper in Link lines and A005563, A217571, A217575. - Takumi Sato, Oct 09 2012 LINKS Takumi Sato, Classification of Natural Numbers EXAMPLE As a triangle (see the first comment) this begins: 9; 16, 17; 25, 26, 27; 36, 37, 38, 39; 49, 50, 51, 52, 53; 64, 65, 66, 67, 68, 69; 81, 82, 83, 84, 85, 86, 87; 100, 101, 102, 103, 104, 105, 106, 107; etc. [Bruno Berselli, Oct 12 2012] PROG (Visual Basic in Excel) Sub A217570() Dim x As Long, n As Long, y As Long, i As Long x = InputBox("Count to") For n = 2 To x y = Int(Sqr(n)) If y = Int(n / y) Then GoTo L1 GoTo L2 L1: If y = Int(n / (y - 1)) - 1 Then i = i + 1 Cells(i, 1) = n End If L2: Next n End Sub (PARI) is_A217570(n)={ n>3 & n\(n=sqrtint(n)-1)==n+2}  \\ - M. F. Hasler, Oct 09 2012 CROSSREFS Cf. A005563, A217571, A217575. Sequence in context: A201266 A231977 A269563 * A274188 A335437 A034040 Adjacent sequences:  A217567 A217568 A217569 * A217571 A217572 A217573 KEYWORD nonn AUTHOR Takumi Sato, Oct 07 2012 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.

Last modified January 21 10:05 EST 2022. Contains 350476 sequences. (Running on oeis4.)