A080530 - OEIS

%I #3 Mar 30 2012 18:41:15

%S 207,207,211,211,215,215,219,223,227,227,231,235,239,243,247,251,255,

%T 259,263,267,271

%N Number of nucleons in longest known radioactive decay series ending with Lead 207 ("actinium series"), reversed.

%C The numbers are all equivalent to 3 mod 4. The sequence was submitted reversed, as it is open in the past. It is unknown if reversed decay series are finite (the "island of stability" hypothesis).

%H C. Heilman, <a href="http://chemlab.pc.maricopa.edu/periodic/periodic.html">The Pictorial Periodic Table</a>

%F a(n)=A080534(n)+A080538(n).

%Y Cf. A080529, A080531, A080532.

%K nonn,hard

%O 0,1

%A _Ralf Stephan_, Feb 20 2003