A224866 Numbers of the form m*rad(m)+1, where rad = A007947 (squarefree kernel).

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

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

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.

Cf. A001694, A078310, A007947.

Sequence in context: A191776 A095347 A249353 * A348167 A159073 A088343

Adjacent sequences: A224863 A224864 A224865 * A224867 A224868 A224869

Keyword

nonn

Author

Reinhard Zumkeller, Jul 23 2013

Status

approved