A126836 Ramanujan numbers (A000594) read mod 7.

1, 4, 0, 5, 0, 0, 0, 4, 2, 0, 1, 0, 0, 0, 0, 3, 0, 1, 0, 0, 0, 4, 4, 0, 4, 0, 0, 0, 2, 0, 0, 3, 0, 0, 0, 3, 4, 0, 0, 0, 0, 0, 2, 5, 0, 2, 0, 0, 0, 2, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 1, 0, 2, 0, 0, 0, 0, 4, 0, 4, 0, 0, 0, 0, 1, 0, 4, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 2, 6, 0, 0, 0, 0, 0

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

R. P. Bambah, Ramanujan’s function tau(n)—A congruence property, Bull. Amer. Math. Soc. 53 (1947), 764-765.

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*sigma_3(n) mod 7. - Michel Marcus, Apr 25 2016

Mathematica

Mod[RamanujanTau@ #, 7] &@ Range@ 120 (* Michael De Vlieger, Apr 25 2016 *)

Prog

(PARI) a(n) = ramanujantau(n) % 7; \\ Amiram Eldar, Jan 05 2025

Crossrefs

Cf. A000594, A001158.

Cf. this sequence (mod 7^1), A126837 (mod 7^2), A126838 (mod 7^3).

Sequence in context: A005075 A103638 A129821 * A055241 A055242 A200295

Adjacent sequences: A126833 A126834 A126835 * A126837 A126838 A126839

Keyword

nonn,changed

Author

N. J. A. Sloane, Feb 25 2007

Status

approved