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%I #22 Dec 21 2022 21:24:19
%S 6227180929,6227182993,6227186509,6227199361,6227220691,6227229637,
%T 6227245393,6227246107,6227260969,6227267713,6227268799,6227279341,
%U 6227280491,6227288461,6227311397,6227314111,6227327761,6227351861,6227355097,6227376241,6227447761,6227454979
%N Numbers k such that phi(k) = 13! where phi is the Euler totient function (A000010).
%C A055487(13) = 6227180929 is the first term in the sequence.
%C A165774(13) = 37020293310 is the last term in the sequence.
%H Project Euler, <a href="https://projecteuler.net/problem=248">Problem 248. Numbers for which Euler's totient function equals 13!</a>.
%o (Python)
%o from sympy import totient
%o def isok(k): return totient(k) == 6227020800
%Y Cf. A000010, A055487, A165774.
%K nonn,fini
%O 1,1
%A _Darío Clavijo_, Nov 18 2022
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