OFFSET
1,1
COMMENTS
Or numbers n such that n^2 + (n+1)^2 + ... + (n+k)^2 is composite for all k>=0.
For a generalization see comment in A256581.
MATHEMATICA
Select[Range[2, 200], !PrimeQ[2 #^2 + 2 # + 1] && !PrimeQ[3 #^2 + 6 # + 5] && !PrimeQ[6 #^2 + 30 # + 55] &] (* Vincenzo Librandi, Apr 01 2015 *)
Select[Range[200], AllTrue[{2#^2+2#+1, 3#^2+6#+5, 6#^2+30#+55}, CompositeQ]&] (* Harvey P. Dale, Jul 15 2021 *)
PROG
(Magma) [n: n in [0..130] | not IsPrime(2*n^2+2*n+1) and not IsPrime(3*n^2+6*n+5) and not IsPrime(6*n^2+30*n+55)]; // Vincenzo Librandi, Apr 01 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladimir Shevelev, Mar 31 2015
EXTENSIONS
More terms from Peter J. C. Moses, Mar 31 2015
STATUS
approved