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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A215454 a(n) = least positive k such that n^2 divides k! 0
 1, 4, 6, 6, 10, 6, 14, 8, 9, 10, 22, 6, 26, 14, 10, 10, 34, 9, 38, 10, 14, 22, 46, 8, 20, 26, 15, 14, 58, 10, 62, 12, 22, 34, 14, 9, 74, 38, 26, 10, 82, 14, 86, 22, 10, 46, 94, 10, 28, 20, 34, 26, 106, 15, 22, 14, 38, 58, 118, 10, 122, 62, 14, 16, 26, 22, 134, 34 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Indices n such that a(n)=n: 1 followed by A074845. LINKS EXAMPLE a(12): least positive k such that 144 divides k! is k=6, 6!=720. So a(12)=6. MATHEMATICA Module[{nn=200, f}, f=Range[nn]!; Position[f, #]&/@Table[SelectFirst[ f, Divisible[ #, n^2]&], {n, nn}]]//Flatten (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 11 2018 *) PROG (Python) TOP = 77 ii = [0]*TOP for i in range(1, TOP):     ii[i] = i*i f = k = y = 1 res = [-1]*TOP while y

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 August 10 10:09 EDT 2022. Contains 356039 sequences. (Running on oeis4.)