OFFSET
1,1
EXAMPLE
T(20) = 210, T(21) = 231, T(22) = 253, and 210231253 is prime, so 20 is a term;
T(31) = 496, T(32) = 528, T(33) = 561, and 496528561 is prime, so 31 is a term.
MATHEMATICA
p3cQ[n_]:=Module[{c1=(n(n+1))/2, c2=((n+1)(n+2))/2, c3=((n+2)(n+3))/2}, PrimeQ[FromDigits[Flatten[IntegerDigits/@{c1, c2, c3}]]]]; Select[Range[ 1250], p3cQ] (* Harvey P. Dale, Sep 13 2011 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Mar 28 2009
STATUS
approved