%I #11 Jul 01 2018 21:16:50
%S 0,1,3,6,10,36,66,136,300,630,666,3003,3160,10011,13366,16110,60031,
%T 66066,106030,163306,303031,333336,336610,600060,630003,1010331,
%U 1030330,1063611,1313010,3306306,3316600,6601161,10006101,11066160,13336030,16310616,30330366
%N Triangular numbers with every digit a triangular number.
%H Harry J. Smith, <a href="/A062100/b062100.txt">Table of n, a(n) for n = 1..200</a>
%e a(6) = 36 is a triangular number, 3 and 6 are also triangular numbers.
%t Select[FromDigits/@Tuples[{0,1,3,6},8],IntegerQ[(Sqrt[8#+1]-1)/2]&] (* _Harvey P. Dale_, Nov 05 2011 *)
%o (PARI) TD(x)= { return(x==0 || x==1 || x==3 || x==6) } { n=t=0; for (m=0, 10^9, t+=m; x=t; td=1; while (x>9, d=x-10*(x\10); if (!TD(d), td=0; break); x\=10); if (td && TD(x), write("b062100.txt", n++, " ", t); if (n==200, break)) ) } \\ _Harry J. Smith_, Aug 01 2009
%Y Cf. A000217.
%K nonn,base,easy
%O 1,3
%A _Amarnath Murthy_, Jun 16 2001
%E Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 22 2001
%E Offset corrected by _Harry J. Smith_, Aug 01 2009
%E More terms from _Harvey P. Dale_, Nov 05 2011