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A126825 Ramanujan numbers (A000594) read mod 3. 2
1, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 1, 0, 0, 2, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,7
COMMENTS
a(4*n) = a(n) (see Corollary 2.2. p. 726 of Ewell link). - Michel Marcus, Dec 23 2012
LINKS
R. P. Bambah and S. Chowla, Congruence properties of Ramanujan’s function tau(n), Bull. Amer. Math. Soc. 53 (1947), 950-955.
John A. Ewell, New representations of Ramanujan's tau function, Proc. Amer. Math. Soc. 128 (2000), 723-726
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) = sigma(n) mod 3, for n coprime to 3. - Michel Marcus, Apr 26 2016
MAPLE
seq(modp(numtheory:-sigma(n), 3)*(1-abs(mods(n-1, 3))), n=1..105); # Peter Luschny, Apr 26 2016
MATHEMATICA
Mod[RamanujanTau@ #, 3] & /@ Range@ 105 (* Michael De Vlieger, Apr 26 2016 *)
CROSSREFS
Sequence in context: A045837 A319687 A374217 * A045833 A117896 A356735
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 25 2007
STATUS
approved

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Last modified July 17 23:53 EDT 2024. Contains 374377 sequences. (Running on oeis4.)