OFFSET
1,1
COMMENTS
These are sometimes called "deletable composites".
LINKS
T. D. Noe, Table of n, a(n) for n = 1..10000
Dave Radcliffe, Python program/code
EXAMPLE
142 is composite. If the 1 is deleted, 42 is composite. If the 4 is deleted, 12 is composite. If the 2 is deleted, 14 is composite. Therefore, 142 is included in this sequence.
MATHEMATICA
prime01Q[n_] := n == 0 || n == 1 || PrimeQ[n]; okQ[n_] := Module[{d = IntegerDigits[n]}, Not[Or @@ prime01Q /@ Table[FromDigits[Delete[d, i]], {i, Length[d]}]]]; Select[Range[215], ! PrimeQ[#] && okQ[#] &] (* T. D. Noe, Aug 14 2013 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Derek Orr, Aug 04 2013
STATUS
approved