%I #20 Jan 06 2025 04:07:27
%S 1,9,10,2,1,2,9,0,9,9,1,9,4,4,10,7,9,4,0,2,2,9,10,0,7,3,5,7,0,2,7,8,
%T 10,4,9,7,3,0,7,0,3,7,5,2,9,2,8,4,8,8,2,8,5,1,1,0,0,0,5,9,1,8,4,3,4,2,
%U 4,7,1,4,8,0,4,5,4,0,9,8,1,7,1,5,5,4,9,1,0,0,4,4,3,9,4,6,0,3,4,6,9,3,2,7,6
%N Ramanujan numbers (A000594) read mod 11.
%H Seiichi Manyama, <a href="/A126839/b126839.txt">Table of n, a(n) for n = 1..10000</a>
%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.
%F a(n) = A006571(n) (mod 11), n >= 1. For a proof see the Cowles link under A006571. See also the _R. J. Mathar_ formula there. - _Wolfdieter Lang_, Feb 16 2016
%t a[n_] := Mod[RamanujanTau[n], 11]; Array[a, 100] (* _Amiram Eldar_, Jan 05 2025 *)
%o (PARI) a(n) = ramanujantau(n) % 11; \\ _Amiram Eldar_, Jan 05 2025
%Y Cf. A000594, this sequence (mod 11^1), A126840 (mod 11^2), A126841 (mod 11^3), A006571.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Feb 25 2007