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 A179653 Triangular numbers (A000217) which are also primes in carryless digital root arithmetic in base 10 (A169911). 0

%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

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Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)