OFFSET
1,3
FORMULA
a(n) = (2^n - (-1)^n)^n / 3^n.
One-third the logarithmic derivative of A211893.
MATHEMATICA
Module[{nn=20}, #[[1]]^#[[2]]&/@Thread[{Rest[LinearRecurrence[{1, 2}, {0, 1}, nn+1]], Range[nn]}]] (* Harvey P. Dale, Jan 17 2022 *)
PROG
(PARI) {a(n)=(2^n-(-1)^n)^n/3^n}
for(n=1, 15, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 06 2013
STATUS
approved