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Revision History for A249407

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A249407

Numbers not in A249406.
(history; published version)

#8 by Joerg Arndt at Sun May 14 11:56:06 EDT 2017

STATUS

reviewed

approved

#7 by Michel Marcus at Sun May 14 11:50:19 EDT 2017

STATUS

proposed

reviewed

#6 by Eric Rowland at Sun May 14 11:48:05 EDT 2017

STATUS

editing

proposed

#5 by Eric Rowland at Sun May 14 11:47:38 EDT 2017

COMMENTS

see A4494011 A249411 for numbers of the form m*(m+1).

STATUS

approved

editing

Discussion

Sun May 14

11:48

Eric Rowland: Fixed sequence number

#4 by N. J. A. Sloane at Sat Nov 01 10:53:57 EDT 2014

STATUS

editing

approved

#3 by Reinhard Zumkeller at Fri Oct 31 15:34:40 EDT 2014

COMMENTS

Primes are a subsequence, but semiprimes (cf. A001358) are not: first missing: A249406(1)=6=2*3, A249406(732)=2196323=1481*1483, A249406(1263)=6502499=2549*2551, A249406(1472)=8820899=2969*2971, A249406(1756)=12531599=3539*3541, ... ;

see A4494011 for numbers of the form m*(m+1).

PROG

(Haskell)

import Data.List ((\\))

a249407 n = a249407_list !! (n-1)

a249407_list = f [2..] where

f ws@(u:v:_) = u : v : f (ws \\ [u, v, u * v])

CROSSREFS

Cf. A249406 (complement), A000040 (subsequence), A001358.

#2 by Reinhard Zumkeller at Fri Oct 31 15:32:16 EDT 2014

NAME

allocated for Reinhard ZumkellerNumbers not in A249406.

DATA

2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70

OFFSET

1,1

KEYWORD

allocated

nonn

AUTHOR

Reinhard Zumkeller, Oct 31 2014

STATUS

approved

editing

#1 by Reinhard Zumkeller at Mon Oct 27 20:53:31 EDT 2014

NAME

allocated for Reinhard Zumkeller

KEYWORD

allocated

STATUS

approved