OFFSET
1,3
COMMENTS
Same as the number of elements of GF(3^n) with trace 2 and subtrace 0.
LINKS
PROG
(Sage)
def a(n):
if n==1: return 1
ans = 0
for x in GF(3^n):
if x.charpoly().coefficients(sparse=False)[-3:-1]==[0, 1]: ans += 1
return ans # Robin Visser, Dec 28 2024
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Frank Ruskey and Nate Kube, Aug 19 2002
EXTENSIONS
Terms a(13)-a(16) corrected, unverified terms a(17)-a(20) removed. Based on the original Data in A074000-A074005, a(17)-a(20) are possibly equal to 14351094, 43046721, 129127041, 387440172. - Andrey Zabolotskiy, Nov 11 2024
Terms a(17)-a(20) recomputed and added again (verified that all the terms a(17)-a(20) conjectured by Andrey Zabolotskiy are correct), and added term a(21). - Robin Visser, Dec 28 2024
STATUS
approved