An Elemental Puzzle

davar55 · 2007-03-06, 22:10

I'm almost embarassed to try this one ...

What do the following 11 elements, and no others (so far)
have in common?

Actinium, Aluminum, Bohrium, Boron, Chlorine, Gallium, Helium,
Lithium, Nitrogen, Potassium, and Promethium.

davieddy · 2007-03-06, 22:30

Is the isotope relevant?

m_f_h · 2007-03-07, 01:49

Hmmm...
Their atomic number is a Mersenne prime exponent.

cheesehead · 2007-03-07, 01:59

So, this is your third in a series that began with

http://mersenneforum.org/showthread.php?t=5503

and

http://mersenneforum.org/showthread.php?t=5557 ?

2007-03-06, 22:10	#1
davar55 May 2004 New York City 5·7·11² Posts	An Elemental Puzzle I'm almost embarassed to try this one ... What do the following 11 elements, and no others (so far) have in common? Actinium, Aluminum, Bohrium, Boron, Chlorine, Gallium, Helium, Lithium, Nitrogen, Potassium, and Promethium.

2007-03-07, 01:49	#3
m_f_h Feb 2007 660₈ Posts	very funny Hmmm... Their atomic number is a Mersenne prime exponent.

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2007-03-06, 22:30	#2
davieddy "Lucan" Dec 2006 England 2·3·13·83 Posts	Is the isotope relevant?

2007-03-07, 01:59	#4
cheesehead "Richard B. Woods" Aug 2002 Wisconsin USA 2²·3·641 Posts	So, this is your third in a series that began with http://mersenneforum.org/showthread.php?t=5503 and http://mersenneforum.org/showthread.php?t=5557 ?