A126831 Ramanujan numbers (A000594) read mod 2187.

1, 2163, 252, 715, 456, 513, 752, 1374, 81, 2178, 984, 846, 1817, 1635, 1188, 799, 612, 243, 1982, 177, 1422, 441, 1284, 702, 1195, 132, 729, 1865, 1299, 2106, 1313, 1224, 837, 621, 1740, 1053, 965, 546, 801, 1062, 573, 864, 689, 1533, 1944, 1989, 75, 144, 264, 1938

Offset

1,2

References

M. H. Ashworth, Congruence and identical properties of modular forms, Diss. University of Oxford, 1968.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

H. P. F. Swinnerton-Dyer, On l-adic representations and congruences for coefficients of modular forms, pp. 1-55 of Modular Functions of One Variable III (Antwerp 1972), Lect. Notes Math., 350, 1973.

Formula

a(n) == n^(-620) * sigma_1231(n) for n == 2 (mod 3) (Ashworth, 1968). - Amiram Eldar, Jan 05 2025

Mathematica

Mod[RamanujanTau[Range[50]], 2187] (* Harvey P. Dale, Jan 15 2022 *)

Prog

(PARI) a(n) = ramanujantau(n) % 2187; \\ Amiram Eldar, Jan 05 2025

Crossrefs

Cf. A000594.

Sequence in context: A116074 A252563 A035872 * A161998 A020421 A203736

Adjacent sequences: A126828 A126829 A126830 * A126832 A126833 A126834

Keyword

nonn

Author

N. J. A. Sloane, Feb 25 2007

Status

approved