A309979 Hash Parker numbers: Integers whose real 32nd root's first six nonzero digits (after the decimal point) rearranged in ascending order are equal to 234477.

4, 1191, 2340, 4915, 8101, 8703, 13937, 13952, 14029, 14041, 25111, 25127, 26062, 26203, 26324, 26479, 26490, 27934, 28077, 28195, 50506, 50536, 52216, 52359, 52892, 55703, 55957, 56030, 56059, 56075, 56178, 56244, 56566, 56577, 74747, 75877, 75952, 75996, 80752, 80764, 80765

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Matt Parker's YouTube Video, The A4 Paper Puzzle

Example

4^(1/32) = 1.0442737824274138...
Rearranging 442737 in ascending order gives 234477.
1191^(1/32) = 1.2477346... -> 247734 -> 234477;
2340^(1/32) = 1.2743478... -> 274347 -> 234477.

Mathematica

Select[Range[81000], With[{c=RealDigits[Surd[#, 32], 10, 20]/.(0->Nothing)}, Sort[Take[Drop[c[[1]], c[[2]]], 6]]=={2, 3, 4, 4, 7, 7}]&]//Quiet (* Harvey P. Dale, Jun 22 2025 *)

Prog

(Haskell)
import Data.List
hash :: Double -> Inthash = read . sort . take 6 . filter (/='0') . drop 1 . dropWhile (/='.') . show . (** 0.03125)
main :: IO ()main = print $ map (floor . fst) . filter ((==234477) . snd) $ map (\x -> (x, hash x)) [2..1000000]

Crossrefs

Sequence in context: A371603 A248656 A357512 * A221383 A338104 A198899

Adjacent sequences: A309976 A309977 A309978 * A309980 A309981 A309982

Keyword

nonn,base

Author

Dan Dart, Aug 25 2019

Status

approved