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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 23 2013
STATUS
approved