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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: A008077 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

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Last modified July 4 14:59 EDT 2015. Contains 259210 sequences.