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A348644
a(n) = (18*n + 1)*(24*n + 1)*(144*n + 11).
3
11, 73625, 542087, 1778645, 4156547, 8049041, 13829375, 21870797, 32546555, 46229897, 63294071, 84112325, 109057907, 138504065, 172824047, 212391101, 257578475, 308759417, 366307175, 430594997, 501996131, 580883825, 667631327, 762611885, 866198747, 978765161, 1100684375
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.
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