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A002616 Reduced totient function (divided by 2).
(Formerly M0128 N0052)
3
1, 1, 2, 1, 3, 1, 3, 2, 5, 1, 6, 3, 2, 2, 8, 3, 9, 2, 3, 5, 11, 1, 10, 6, 9, 3, 14, 2, 15, 4, 5, 8, 6, 3, 18, 9, 6, 2, 20, 3, 21, 5, 6, 11, 23, 2, 21, 10, 8, 6, 26, 9, 10, 3, 9, 14, 29, 2, 30, 15, 3, 8, 6, 5, 33, 8, 11, 6, 35, 3, 36, 18, 10, 9, 15, 6, 39, 2, 27, 20, 41, 3, 8, 21, 14, 5, 44, 6, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET
3,3
COMMENTS
A046073 is a similar sequence (the first difference occurs at position 61). - Artur Jasinski, Apr 05 2008
REFERENCES
D. H. Lehmer, Guide to Tables in the Theory of Numbers. Bulletin No. 105, National Research Council, Washington, DC, 1941, pp. 7-10.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
A. Cauchy, Mémoire sur la résolution des équations indéterminées du premier degré en nombres entiers, Oeuvres Complètes. Gauthier-Villars, Paris, 1882-1938, Series (2), Vol. 12, pp. 9-47.
FORMULA
a(n) = A002322(n)/2.
MATHEMATICA
Table[CarmichaelLambda[k + 2]/2, {k, 130}] (* Artur Jasinski, Apr 05 2008 *)
PROG
(Haskell)
a002616 = flip div 2 . a002322 -- Reinhard Zumkeller, Sep 02 2014
(PARI) a(n) = lcm(znstar(n)[2])/2; \\ Michel Marcus, May 22 2022
CROSSREFS
Cf. A002322.
Sequence in context: A075825 A309155 A007735 * A046073 A309786 A162912
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Vladeta Jovovic, Apr 04 2002
STATUS
approved

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Last modified March 19 01:57 EDT 2024. Contains 370952 sequences. (Running on oeis4.)