%I
%S 3,6,10,15,21,28,45,55,78,91,105,136,406,496,528,595,703,741,1035,
%T 1081,1225
%N Triangular numbers (A000217) which are also primes in carryless digital root arithmetic in base 10 (A169911).
%C The complement, triangular numbers (A000217) which are not primes in carryless digital root arithmetic in base 10 (A169911), begins {1, 36, 66, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 435, 465, ...}.
%H <a href="/index/Ca#CARRYLESS">Index entries for sequences related to carryless arithmetic</a>
%F A000217 INTERSECTION A169911.
%e 1, though triangular, is a unit, not a prime, in standard or carryless arithmetic.
%e 36 is triangular, A000217(8), yet not in A169911 since in carryless digital root arithmetic in base 10 we have 3*15 = 36 where both 3 and 15 are primes, and 3*18=36.
%e Similarly, 66 is triangular, A000217(11), yet not in A169911.
%Y Cf. A000217, A169911,
%K nonn,less,base,more
%O 1,1
%A _Jonathan Vos Post_, Jul 22 2010
