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A058988 For a rational number p/q let f(p/q) = p*q divided by number of divisors of p+q; a(n) is obtained by iterating f, starting at n/1, until an integer is reached, or if no integer is ever reached then a(n) = 0. 4
1, 1, 1, 2, 30, 3, 14, 12, 18, 5, 33, 6, 26, 21, 3, 8, 51, 9, 38, 5, 28, 11, 92, 8, 50, 0, 9, 14, 116, 15, 93, 8, 66, 17, 105, 18, 74, 0, 156, 20, 492, 21, 86, 22, 60, 23, 0, 16, 147, 0, 17, 26, 212, 27, 330, 14, 114, 29, 354, 30, 61, 186, 9, 16, 260, 33, 201, 17, 138, 35, 426 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

P. Schogt, The Wild Number Problem: math or fiction?, arXiv preprint arXiv:1211.6583, 2012. - From N. J. A. Sloane, Jan 03 2013

PROG

(Haskell)

import Data.Ratio ((%), numerator, denominator)

a058988 n = numerator $ fst $

  until ((== 1) . denominator . fst) f $ f (fromIntegral n, []) where

  f (x, ys) = if y `elem` ys then (0, []) else (y, y:ys) where

   y = numerator x * denominator x % a000005 (numerator x + denominator x)

-- Reinhard Zumkeller, Aug 29 2014

CROSSREFS

Cf. A058972, A058971, A058977.

Cf. A000005.

Sequence in context: A114533 A180128 A087194 * A292879 A267131 A078690

Adjacent sequences:  A058985 A058986 A058987 * A058989 A058990 A058991

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jan 17 2001

EXTENSIONS

More terms from Naohiro Nomoto, Jul 20 2001

STATUS

approved

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Last modified January 20 03:32 EST 2019. Contains 319323 sequences. (Running on oeis4.)