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%I #19 Jul 11 2021 04:44:20
%S 0,7,56,357,2464,16835,118104,823585,5767328,40354335,282492280,
%T 1977326813,13841410464,96889010491,678223896728,4747561544985,
%U 33232936339456,232630513987319,1628413638500376,11398895185373269
%N a(n) = Sum_{d|n} phi(d)*7^(n/d).
%H Seiichi Manyama, <a href="/A054614/b054614.txt">Table of n, a(n) for n = 0..1000</a>
%F a(n) = Sum_{k=1..n} 7^gcd(n,k). - _Ilya Gutkovskiy_, Apr 16 2021
%o (PARI) a(n) = sumdiv(n, d, eulerphi(d)*7^(n/d)); \\ _Michel Marcus_, Jul 11 2021
%Y Column k=7 of A185651.
%Y Cf. A054626.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Apr 16 2000
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