OFFSET
1,3
EXAMPLE
51 is pentagonal and 15 is triangular
MATHEMATICA
dtn[L_] := Fold[10#1+#2&, 0, L] tritest[n_] := Module[{t}, t=Floor[N[Sqrt[2n]]]; 2n==t(t+1)] A={0}; For[i=1, i>0, i++, t=i(3i-1)/2; r=dtn[Reverse[IntegerDigits[t]]]; If[tritest[r]&&Mod[t, 10]>0, AppendTo[A, t]; Print[A]]]
Select[Table[(n(3n-1))/2, {n, 0, 194*10^6}], Mod[IntegerReverse[#], 10]!=0&&OddQ[Sqrt[8IntegerReverse[#]+1]]&] (* Requires Mathematica version 10 or later *) (* The program will take a long time to run *) (* Harvey P. Dale, Sep 12 2017 *)
CROSSREFS
KEYWORD
base,more,nonn
AUTHOR
Erich Friedman, Jan 17 2002
EXTENSIONS
a(13)-a(15) from Lars Blomberg, May 18 2011
Description clarified and offset corrected by Lars Blomberg, May 29 2011
STATUS
approved