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COMMENTS
| Prime p divides 3^p - 2^p - 1. 42 = 2*3*7 divides a(n) for n>2. Numbers n such that n divides 3^n - 2^n - 1 are listed in A127072(n) = {1,2,3,4,5,7,8,9,11,13,16,17,19,23,27,29,31,32,37,41,43,45,47,49,53,59,61,64,67,71,73,79,81,83,89,97,...}. Pseudoprimes in A127072(n) include all powers of primes {2,3,7} and some composite numbers that are listed in A127073(n) = {45,245,405,561,637,639,833,891,...}. Numbers n such that n^2 divides 3^n - 2^n - 1 are listed in A127074(n) = {1,2,3,4,7,49,179,619,...}. Numbers n such that n^3 divides 3^n - 2^n - 1 are {1,4,7,...}.
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