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%I #4 May 16 2013 02:05:09
%S 2,3,2,11,19,3,5,0,71,23,109,131,17,181,2,239,271,307,0,379,3,13,127,
%T 61,67,163,701,47,811,97,37,991,0,31,0,79,83,0,41,7,0,191,37,0,5,83,
%U 541,251,2351,613,71,0,0,2861,743,3079,3191,367,0,3539,229,0,977,0,4159
%N Least prime number p such that p*triangular(n) is a triangular number, or 0 if no such p exists.
%F a(n) <= n^2 + n + 2. For n>0, a(n) <= n^n + n + 1.
%e Least prime p such that triangular(3)*p is a triangular number is p=11, so a(3) = 11.
%Y Cf. A000217, A068084, A225502.
%K nonn
%O 0,1
%A _Alex Ratushnyak_, May 16 2013
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