

A071228


a(n) = n*(nth 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
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OFFSET

1,1


COMMENTS

Complement of A171521(n). [From Jaroslav Krizek, Dec 13 2009]


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000


FORMULA

a(1)= 1*4, a(2)= 2*6, a(3)= 3*9, a(4) = 4*10
a(n) = A000027(n) * A002808(n) = n * A002808(n). [From Jaroslav Krizek, Dec 13 2009]


MAPLE

count := 1: for i from 2 to 100 do if isprime(i) then else printf(`%d, `, i*count); count := count+1 fi: od:


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 and Maple code 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



