This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A071228 a(n) = n*(n-th composite number). 2
 4, 12, 24, 36, 50, 72, 98, 120, 144, 180, 220, 252, 286, 336, 375, 416, 459, 504, 570, 640, 693, 748, 805, 864, 950, 1014, 1080, 1176, 1276, 1350, 1426, 1536, 1617, 1700, 1785, 1872, 1998, 2090, 2184, 2280, 2378, 2520, 2666, 2772, 2880, 2990, 3102 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Complement of A171521(n). - Jaroslav Krizek, Dec 13 2009 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 FORMULA a(n) = n * A002808(n). - Jaroslav Krizek, Dec 13 2009 EXAMPLE a(1)= 1*4, a(2)= 2*6, a(3)= 3*9, a(4) = 4*10. MAPLE count := 1: for i from 2 to 100 do if isprime(i) then else printf(`%d, `, i*count); count := count+1 fi: od: # James A. Sellers, May 28 2002 MATHEMATICA Module[{cn=Select[Range[70], CompositeQ]}, Times@@@Thread[{cn, Range[ Length[ cn]]}]] (* Harvey P. Dale, Nov 13 2014 *) CROSSREFS Sequence in context: A285350 A072389 A218391 * A108997 A159795 A033602 Adjacent sequences:  A071225 A071226 A071227 * A071229 A071230 A071231 KEYWORD nonn AUTHOR Amarnath Murthy, May 17 2002 EXTENSIONS More terms from James A. Sellers, May 28 2002 Edited by N. J. A. Sloane, Jul 02 2008 at the suggestion of R. J. Mathar 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.