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A126826 Ramanujan numbers (A000594) read mod 9. 0
1, 3, 0, 4, 6, 0, 5, 6, 0, 0, 3, 0, 8, 6, 0, 7, 0, 0, 2, 6, 0, 0, 6, 0, 7, 6, 0, 2, 3, 0, 8, 0, 0, 0, 3, 0, 2, 6, 0, 0, 6, 0, 5, 3, 0, 0, 3, 0, 3, 3, 0, 5, 0, 0, 0, 3, 0, 0, 6, 0, 5, 6, 0, 1, 3, 0, 8, 0, 0, 0, 0, 0, 2, 6, 0, 8, 6, 0, 5, 6, 0, 0, 3, 0, 0, 6, 0, 0, 0, 0, 4, 6, 0, 0, 3, 0, 5, 0, 0, 1, 3, 0, 8, 3, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..105.

R. P. Bambah and S. Chowla, A new congruence property of Ramanujan’s function tau(n), Bull. Amer. Math. Soc. 53 (1947), 768-769.

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^2*sigma(n) mod 9. - Michel Marcus, Apr 25 2016

MATHEMATICA

Mod[RamanujanTau@ #, 9] &@ Range@ 120 (* Michael De Vlieger, Apr 25 2016 *)

PROG

(PARI) a(n) = n^2*sigma(n) % 9; \\ Michel Marcus, Apr 26 2016

CROSSREFS

Cf. A000203, A000594.

Sequence in context: A307383 A111486 A192878 * A231983 A231982 A198575

Adjacent sequences:  A126823 A126824 A126825 * A126827 A126828 A126829

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 25 2007

STATUS

approved

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Last modified June 26 09:31 EDT 2022. Contains 354879 sequences. (Running on oeis4.)