The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A225493 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A225493

Numbers having only strong prime factors, cf. A051634.
(history; published version)

#8 by Joerg Arndt at Sat Mar 17 04:08:03 EDT 2018

STATUS

proposed

approved

#7 by Jon E. Schoenfield at Fri Mar 16 23:49:38 EDT 2018

STATUS

editing

proposed

#6 by Jon E. Schoenfield at Fri Mar 16 23:49:35 EDT 2018

CROSSREFS

Cf. A225494 (balanced), A225495 (weak), A225496 (non -balanced).

STATUS

approved

editing

#5 by Reinhard Zumkeller at Thu May 09 11:00:09 EDT 2013

STATUS

editing

approved

#4 by Reinhard Zumkeller at Thu May 09 01:04:22 EDT 2013

FORMULA

Multiplicative closure of A051634.

PROG

(Haskell)

import Data.Set (singleton, fromList, union, deleteFindMin)

a225493 n = a225493_list !! (n-1)

a225493_list = 1 : h (singleton p) ps [p] where

(p:ps) = a051634_list

h s xs'@(x:xs) ys

| m > x = h (s `union` (fromList $ map (* x) (1 : ys))) xs ys

| otherwise = m : h (s' `union` (fromList $ map (* m) ys')) xs' ys'

where ys' = m : ys; (m, s') = deleteFindMin s

CROSSREFS

Cf. A225494 (balanced), A225495 (weak), A225496 (non balanced).

#3 by Reinhard Zumkeller at Thu May 09 01:03:05 EDT 2013

NAME

allocated for Reinhard ZumkellerNumbers having only strong prime factors, cf. A051634.

DATA

1, 11, 17, 29, 37, 41, 59, 67, 71, 79, 97, 101, 107, 121, 127, 137, 149, 163, 179, 187, 191, 197, 223, 227, 239, 251, 269, 277, 281, 289, 307, 311, 319, 331, 347, 367, 379, 397, 407, 419, 431, 439, 451, 457, 461, 479, 487, 493, 499, 521, 541, 557, 569, 587

OFFSET

1,2

LINKS

Reinhard Zumkeller, <a href="/A225493/b225493.txt">Table of n, a(n) for n = 1..5000</a>

KEYWORD

allocated

nonn

AUTHOR

Reinhard Zumkeller, May 09 2013

STATUS

approved

editing

#2 by Reinhard Zumkeller at Wed May 08 14:31:14 EDT 2013

KEYWORD

allocating

allocated

#1 by Reinhard Zumkeller at Wed May 08 14:31:14 EDT 2013

NAME

allocated for Reinhard Zumkeller

KEYWORD

allocating

STATUS

approved