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A126834
Ramanujan numbers (A000594) read mod 125.
4
1, 101, 2, 28, 80, 77, 6, 105, 107, 80, 112, 56, 12, 106, 35, 11, 66, 57, 45, 115, 12, 62, 22, 85, 25, 87, 45, 43, 5, 35, 82, 71, 99, 41, 105, 121, 61, 45, 24, 25, 67, 87, 42, 11, 60, 97, 121, 22, 43, 25, 7, 86, 52, 45, 85, 5, 90, 5, 10, 105, 37, 32, 17, 18, 85, 124, 116, 98, 44
OFFSET
1,2
LINKS
R. P. Bambah and S. Chowla, Congruence properties of Ramanujan’s function tau(n), Bull. Amer. Math. Soc. 53 (1947), 950-955.
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) = (5*n^2*sigma_7(n) - 4*n*sigma_2(n)) mod 125, for n coprime to 5. - Michel Marcus, Apr 26 2016
MATHEMATICA
Mod[RamanujanTau@ #, 125] & /@ Range@ 69 (* Michael De Vlieger, Apr 26 2016 *)
CROSSREFS
Cf. A126832 (mod 5^1), A126833 (mod 5^2), this sequence (mod 5^3), A126835 (mod 5^4).
Sequence in context: A284247 A256826 A036193 * A365928 A318698 A180236
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 25 2007
STATUS
approved