OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
MATHEMATICA
c = Select[Range[2, 150], ! PrimeQ[#] &]; (* A002808 *)
Select[Range[Length[c]], GCD[c[[#]], #] > 1 &] (* A334880 *)
Module[{nn=200, cmps, len}, cmps=Select[Range[nn], CompositeQ]; len=Length[ cmps]; Select[Thread[{Range[len], cmps}], GCD@@#>1&]][[All, 1]] (* Harvey P. Dale, Sep 20 2020 *)
PROG
(PARI) lista(nn) = {my(n=0, list=List()); forcomposite (c=1, nn, n++; if (gcd(n, c) > 1, listput(list, n))); Vec(list); } \\ Michel Marcus, Jul 19 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 17 2020
STATUS
approved