%I
%S 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,
%T 1,1,1,0,1,1,0,1,0,1,1,1,1,1,1,1,1,1,0,1,0,1,0,1,0,1,0,1,0,1,1,1,0,0,
%U 1,1,1,1,1,1,0,1,0,1,0,1,0,1,1,0,1,1,0,0,1,1,1,1,1,0,1,1,0,1,1,0,0,1,0,1,0
%N Triangle T(p,k) read by rows, where p runs through the primes and 1 <= k <= p1. T(p,k) = 1 if the reverse of the basek expansion of p is a prime, otherwise 0.
%C Row p has p1 terms.
%C A very large version of this pyramid, with 1's replaced with white dots and 0's replaced with black dots, shows a very interesting pattern (see link). The author says: "These primes form a pattern similar to an astronomical radiant (the point in the sky from which a meteor shower appears to originate)".
%H C. E. Nichols, <a href="http://www.radiantprimes.com/">Radiant Prime</a>, 2003
%e Writing 11 in bases 1 through 10, we obtain
%e 11111111111,1011,102,23,21,15,14,13,12,11. Reversing these, we obtain
%e 11111111111,1101,201,32,12,51,41,31,21,11. Now 32 (base 4) and 31 (octal) are composite, all others are prime, so the row for 11 reads.
%e 1,1,1,0,1,1,1,0,1,1
%e Triangle begins:
%e .1
%e .1 1
%e .1 1 1 1
%e .1 1 1 1 1 1
%e .1 1 1 0 1 1 1 0 1 1
%e ....
%Y See A089829 for another version.
%K base,easy,nonn,tabf
%O 2,1
%A C. E. Nichols (radprime(AT)radiantprimes.com), Nov 19 2003
%E More terms from _Ray Chandler_, Nov 22 2003
