This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A126830 #10 Jan 05 2025 01:08:35 %S A126830 1,705,252,715,456,513,23,645,81,720,255,117,359,177,459,70,612,243, %T A126830 524,177,693,441,555,702,466,132,0,407,570,648,584,495,108,621,282, %U A126830 324,236,546,72,333,573,135,689,75,486,531,75,144,264,480,405,77,135,0,369,255 %N A126830 Ramanujan numbers (A000594) read mod 729. %D A126830 M. H. Ashworth, Congruence and identical properties of modular forms, Diss. University of Oxford, 1968. %D A126830 Oddmund Kolberg, Congruences for Ramanujan's Function ̈tau(n), Univ. Bergen Årbok Naturvit Rekke, No. 11, 1962. %H A126830 Amiram Eldar, <a href="/A126830/b126830.txt">Table of n, a(n) for n = 1..10000</a> %H A126830 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 A126830 From _Amiram Eldar_, Jan 05 2025: (Start) %F A126830 a(n) == 53 * sigma_11(n) (mod 729) for n == 2 (mod 3) (Kolberg, 1962). %F A126830 a(n) == n^(-620) * sigma_1231(n) for n == 1 (mod 3) (Ashworth, 1968). (End) %t A126830 a[n_] := Mod[RamanujanTau[n], 729]; Array[a, 100] (* _Amiram Eldar_, Jan 05 2025 *) %o A126830 (PARI) a(n) = ramanujantau(n) % 729; \\ _Amiram Eldar_, Jan 05 2025 %Y A126830 Cf. A000594, A013959. %K A126830 nonn %O A126830 1,2 %A A126830 _N. J. A. Sloane_, Feb 25 2007