OFFSET
0,1
REFERENCES
D. E. Knuth, The Art of Computer Programming, Vol. 4A, Addison-Wesley, 2011, Section 7.1.4.
LINKS
FORMULA
a(n) = 2*(2^2^n-1) + Sum_{k=0..n-1} (2^2^(n-k)-2^2^(n-k-1))*(2^2^n-(2^2^(n-k)-1)^2^k).
a(n) < 2^2^n*A327461(n) for n >= 1.
MATHEMATICA
a[n_]:=2(2^2^n-1)+Sum[(2^2^(n-k)-2^2^(n-k-1))*(2^2^n-(2^2^(n-k)-1)^2^k), {k, 0, n-1}]; Array[a, 9, 0] (* Stefano Spezia, Jun 26 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Pontus von Brömssen, Jun 22 2021
STATUS
approved