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A206368
Numbers k such that A206369(k) = A206369(k + 1).
7
1, 20, 116, 135, 171, 194, 740, 1220, 1419, 1803, 1892, 1952, 2696, 3705, 4575, 5186, 7868, 10659, 11247, 17948, 18507, 18548, 19107, 25545, 27405, 29294, 33500, 34371, 37820, 48872, 49184, 53108, 54620, 58652, 61760, 67220, 102296, 104139, 105908, 113576
OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000 (terms 1..100 from Reinhard Zumkeller)
László Tóth, A survey of the alternating sum-of-divisors function, arXiv:1111.4842 [math.NT], 2011-2014.
FORMULA
A206475(a(n)) = 0. - Reinhard Zumkeller, Feb 08 2012
MATHEMATICA
(* b = A206369 *) b[n_] := n*DivisorSum[n, LiouvilleLambda[#]/# &];
Reap[For[n = 1, n <= 120000, n++, If[b[n] == b[n+1], Print[n]; Sow[n] ] ] ][[2, 1]] (* Jean-François Alcover, Dec 04 2017 *)
PROG
(Haskell)
import Data.List (elemIndices)
a206368 n = a206368_list !! (n-1)
a206368_list = map (+ 1) $ elemIndices 0 a206475_list
-- Reinhard Zumkeller, Feb 08 2012
CROSSREFS
Sequence in context: A267843 A271494 A220928 * A377987 A258667 A357042
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 06 2012
STATUS
approved