The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A003057 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A003057

n appears n - 1 times.
(history; published version)

#75 by Joerg Arndt at Wed Jul 27 02:20:09 EDT 2022

STATUS

reviewed

approved

#74 by Michel Marcus at Wed Jul 27 00:54:19 EDT 2022

STATUS

proposed

reviewed

#73 by Jon E. Schoenfield at Tue Jul 26 18:33:54 EDT 2022

STATUS

editing

proposed

#72 by Jon E. Schoenfield at Tue Jul 26 18:33:14 EDT 2022

PROG

(MAGMAMagma) [Round(Sqrt(2*(n-1)))+1: n in [2..60]]; // Vincenzo Librandi, Jun 23 2011

STATUS

proposed

editing

#71 by Chai Wah Wu at Tue Jul 26 18:07:05 EDT 2022

STATUS

editing

proposed

#70 by Chai Wah Wu at Tue Jul 26 18:06:59 EDT 2022

PROG

(Python)

from math import isqrt

def A003057(n): return (k:=isqrt(m:=n-1<<1))+int((m<<2)>(k<<2)*(k+1)+1)+1 # Chai Wah Wu, Jul 26 2022

STATUS

approved

editing

#69 by N. J. A. Sloane at Mon Jan 10 22:38:00 EST 2022

STATUS

proposed

approved

#68 by Allan Bickle at Sun Dec 26 21:58:15 EST 2021

STATUS

editing

proposed

#67 by Allan Bickle at Sun Dec 26 21:58:11 EST 2021

COMMENTS

a(n) is the pair chromatic number of an empty graph with n vertices. (The pair chromatic number of a graph G is the smallest number of colors for which G has a coloring where every vertex has two distinct colors, no adjacent vertices have a common color, and no pair of colors is repeated.) - Allan Bickle, Dec 26 2021

#66 by Allan Bickle at Sun Dec 26 21:57:39 EST 2021

COMMENTS

a(n) is the pair chromatic number of an empty graph. (The pair chromatic number of a graph G is the smallest number of colors for which G has a coloring where every vertex has two distinct colors, no adjacent vertices have a common color, and no pair of colors is repeated.) - _Allan Bickle_, Dec 26 2021

STATUS

proposed

editing