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%I #17 Nov 07 2020 11:42:46
%S 2,3,5,7,23,691
%N Exceptional primes for Ramanujan's tau function.
%C For each exceptional prime p, Ramanujan's tau function tau(n) = A000594(n) satisfies a simple congruence modulo p.
%C The main entry for this subject is A000594.
%C Terms 23 and 691 also appear in A193855. - _Jud McCranie_, Nov 05 2020
%D H. P. F. Swinnerton-Dyer, Congruence properties of tau(n), pp. 289-311 of G. E. Andrews et al., editors, Ramanujan Revisited. Academic Press, NY, 1988.
%H H. P. F. Swinnerton-Dyer, <a href="http://dx.doi.org/10.1007/978-3-540-37802-0_1">On l-adic representations and congruences for coefficients of modular forms</a>, pp. 1-55 of Modular Functions of One Variable III (Antwerp 1972), Lect. Notes Math., 350, 1973.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Ramanujan_tau_function">Ramanujan tau function</a>
%e 691 is an exceptional prime because tau(n) == sum of 11th power of divisors of n mod 691 (see A046694).
%Y Cf. A000594, A046694, A193855.
%K nonn,fini,full
%O 1,1
%A _Jonathan Sondow_, Sep 18 2015
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