OFFSET
0,1
COMMENTS
a(n) is the entry (1,2) of a family of unimodular matrices none of whose entries is 1 or -1, such that when each entry of the matrix is replaced by its cube, the resulting matrix is also unimodular.
In these matrices, the entries (1,3) and (3,1) = 2; the entries (2,3) and (3,2) = 3; the entry (3,3) = 0.
LINKS
Ajai Choudhry, A diophantine problem concerning third order matrices, arXiv:2110.12643 [math.NT], 2021.
Wikipedia, Unimodular matrix
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
PROG
(PARI) a(n) = (18*n + 1)*(24*n + 1)*(144*n + 11);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Marcus, Oct 27 2021
STATUS
approved