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%I #24 Sep 08 2022 08:46:08
%S 4,18,210,2058,175098,1586130,129009090,1161737178,94134790218,
%T 68629840493970,617671248800298,450283768452043890,
%U 36472994178147530850,328256958598444055418,26588814218220014932458,19383245658672820642055730
%N 3^p - 2^p - 1, where p is prime.
%C For p>3, all terms are divisible by 42.
%H Vincenzo Librandi, <a href="/A242083/b242083.txt">Table of n, a(n) for n = 1..320</a>
%F a(n) = abs(A083321(A000040(n)). - _Michel Marcus_, May 05 2014
%t Table[(3^Prime[n] - 2^Prime[n] - 1), {n, 1, 30}]
%t 3^#-2^#-1&/@Prime[Range[20]] (* _Harvey P. Dale_, Aug 05 2016 *)
%o (Magma) [3^p-2^p-1: p in PrimesUpTo(60)]
%o (PARI) a(n) = my(p = prime(n)); 3^p-2^p-1; \\ _Michel Marcus_, May 05 2014
%o (Sage) [3^p-2^p-1 for p in primes(60)] # _Bruno Berselli_, May 12 2014
%Y Cf. A083321, A204768.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, May 04 2014
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