OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} 3^(k*(2*n + 1 - k)/2). - Vaclav Kotesovec, Apr 10 2024
MATHEMATICA
Table[Sum[3^(k*(2*n + 1 - k)/2), {k, 0, n}], {n, 0, 15}] (* Vaclav Kotesovec, Apr 10 2024 *)
Block[{n = 0}, NestList[#*3^++n + 1 &, 1, 15]] (* Paolo Xausa, Apr 19 2024 *)
PROG
(Python)
l = [1]
for i in range(1, 14):
l.append(l[-1]*pow(3, i) + 1)
print(l)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alexandre Herrera, Mar 23 2024
STATUS
approved