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A224866
Numbers of the form m*rad(m)+1, where rad = A007947 (squarefree kernel).
5
2, 5, 9, 10, 17, 26, 28, 33, 37, 50, 65, 73, 82, 101, 109, 122, 126, 129, 145, 170, 197, 201, 217, 226, 244, 257, 289, 290, 325, 344, 362, 393, 401, 433, 442, 485, 501, 513, 530, 577, 626, 649, 676, 677, 730, 785, 801, 842, 865, 901, 962, 969, 973, 1001
OFFSET
1,1
COMMENTS
A078310 in natural order.
LINKS
FORMULA
a(n) = A001694(n) + 1.
MATHEMATICA
powQ[n_] := n == 1 || AllTrue[FactorInteger[n][[;; , 2]], # > 1 &]; Select[Range[1001], powQ[# - 1] &] (* Amiram Eldar, Jul 31 2022 *)
PROG
(Haskell)
a224866 n = a224866_list !! (n-1)
a224866_list = [x | x <- [2..] , let x' = x - 1, let k = a007947 x',
let (y, m) = divMod x' k, m == 0, a007947 y == k]
(PARI) is(n) = n>1 && ispowerful(n-1) \\ Charles R Greathouse IV, Aug 08 2013, corrected by Amiram Eldar, Jul 31 2022
CROSSREFS
Subsequences: A078325, A078324.
Sequence in context: A191776 A095347 A249353 * A348167 A159073 A088343
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 23 2013
STATUS
approved