OFFSET
1,2
MATHEMATICA
del[lst_, k_] := lst[[ Select[ Range[ Length[ lst]], Mod[ #, k] != 0 &]]]; For[ k = 2; s = Range[10000], k <= Length[s], k++, s = del[s, k]]; (Drop[s, 1] - Drop[s, -1])/2
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Nov 15 2004
EXTENSIONS
More terms from Robert G. Wilson v, Nov 15 2004
STATUS
approved