OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..100
Antreas Hatzipolakis and Giovanni Resta, Number of Equilateral Triangles in Regular 3n-gon, Postings to the Sequence Fans Mailing List, Apr 08 2013
Andrew Howroyd, PARI Program, Sep 2024.
Giovanni Resta, Illustration for a(3) = 69
FORMULA
Conjecture: For odd n, a(n) = n*(n+1)^3/2 - 3*n^2. - Vilim Lendvaj, Jul 24 2024
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
N. J. A. Sloane, Mar 07 2014
EXTENSIONS
a(6)-a(24) from Luca Petrone, Mar 28 2017
Corrected and extended by Vilim Lendvaj, Jul 24 2024
a(26) onwards from Andrew Howroyd, Sep 26 2024
STATUS
approved