# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a071228 Showing 1-1 of 1 %I A071228 #31 Jun 25 2022 21:43:19 %S A071228 4,12,24,36,50,72,98,120,144,180,220,252,286,336,375,416,459,504,570, %T A071228 640,693,748,805,864,950,1014,1080,1176,1276,1350,1426,1536,1617,1700, %U A071228 1785,1872,1998,2090,2184,2280,2378,2520,2666,2772,2880,2990,3102 %N A071228 a(n) = n*(n-th composite number). %C A071228 Complement of A171521. - _Jaroslav Krizek_, Dec 13 2009 %H A071228 Harvey P. Dale, Table of n, a(n) for n = 1..1000 %F A071228 a(n) = n * A002808(n). - _Jaroslav Krizek_, Dec 13 2009 %e A071228 a(1)= 1*4, a(2)= 2*6, a(3)= 3*9, a(4) = 4*10. %p A071228 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 %t A071228 Module[{cn=Select[Range[70],CompositeQ]},Times@@@Thread[{cn, Range[ Length[ cn]]}]] (* _Harvey P. Dale_, Nov 13 2014 *) %o A071228 (PARI) lista(nn) = {my(nc = 0); forcomposite(c=1, nn, nc ++; print1(c*nc, ", "););} \\ _Michel Marcus_, Aug 31 2019 %Y A071228 Cf. A002808, A033286, A171521. %Y A071228 Partial sums of A092930. %K A071228 nonn %O A071228 1,1 %A A071228 _Amarnath Murthy_, May 17 2002 %E A071228 More terms from _James A. Sellers_, May 28 2002 %E A071228 Edited by _N. J. A. Sloane_, Jul 02 2008 at the suggestion of _R. J. Mathar_ # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE