OFFSET
1,2
COMMENTS
Elements corresponding to the initial sequence terms are hydrogen, carbon, silicon, cobalt, rhodium, ytterbium, and nobelium. However, there may not be a physical realization for higher terms.
LINKS
Index entries for linear recurrences with constant coefficients, signature (3,-2,-2,3,-1).
FORMULA
a(n) = (4*n^3 + 18*n^2 + 32*n + 3*(-1)^n - 27)/24.
G.f.: x*(1 + 3*x - 2*x^2 - x^3 + x^4)/((1 - x)^4*(1 + x)). - Stefano Spezia, Dec 31 2021
EXAMPLE
For n=1, hydrogen (with atomic number 1) is the first element of two middle elements in the 1st row of periodic table.
For n=2, carbon (with atomic number 6) is the first element of the two middle elements in the 2nd row of periodic table.
In general, the n-th number is the addition of the atomic number of the first lower noble element plus half the number of elements in the current row of the periodic table.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Yigit Oktar, Dec 31 2021
STATUS
approved