A185026 The first bisection of the sequence A002616 of reduced totients.

1, 2, 3, 3, 5, 6, 2, 8, 9, 3, 11, 10, 9, 14, 15, 5, 6, 18, 6, 20, 21, 6, 23, 21, 8, 26, 10, 9, 29, 30, 3, 6, 33, 11, 35, 36, 10, 15, 39, 27, 41, 8, 14, 44, 6, 15, 18, 48, 15, 50, 51, 6, 53, 54, 18, 56, 22, 6, 24, 55, 20, 50, 63, 21, 65, 9, 18, 68, 69, 23, 30, 14, 21, 74, 75, 24, 30, 78, 26, 33

Offset

1,2

Comments

Fixed points n where n=a(n) are n=1, 2, 3, 5, 6, 8, 9, 11,... = A005097.

There are pairs of the consecutive terms of the form (3*k,k): 6,2, 9,3, 15,5, 18,6, 33,11, 54,18, 63,21, 69,23, 78,26, ... . It seems that k is the set of all A174100(n), n>1, plus a few exceptions (like the pair 126, 42).

Links

G. C. Greubel, Table of n, a(n) for n = 1..5000

Formula

a(n) = A002616(2*n+1).

Maple

A185026 := proc(n)
        numtheory[lambda](2*n+1)/2 ;
end proc: # R. J. Mathar, Mar 27 2013

Mathematica

Table[ CarmichaelLambda[2*n + 1]/2, {n, 1, 80}] (* Jean-François Alcover, Apr 04 2013 *)

Crossrefs

Sequence in context: A281363 A050976 A053447 * A289630 A023160 A085312

Adjacent sequences: A185023 A185024 A185025 * A185027 A185028 A185029

Keyword

nonn

Author

Paul Curtz, Dec 24 2012

Status

approved