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A245027
Divisors of 7^12 - 1.
3
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 15, 16, 18, 19, 20, 24, 25, 26, 30, 32, 36, 38, 39, 40, 43, 45, 48, 50, 52, 57, 60, 65, 72, 75, 76, 78, 80, 86, 90, 95, 96, 100, 104, 114, 117, 120, 129, 130, 144, 150, 152, 156, 160, 171, 172, 180, 181, 190, 195, 200, 208
OFFSET
1,2
COMMENTS
Number of divisors of k^12-1 for k = 2..20: 24 (2), 80 (3), 96 (4), 240 (5), 128 (6), 864 (7), 512 (8), 384 (9), 256 (10), 1920 (11), 256 (12), 960 (13), 384 (14), 448 (15), 768 (16), 1792 (17), 768 (18), 3840 (19), 384 (20).
The following triangular numbers belong to this sequence: 1, 3, 6, 10, 15, 36, 45, 78, 120, 171, 190, 300, 325, 741, 780, 2080, 2850, 4560, 8385, 14706, 16290, 5915080, 1730160900.
EXAMPLE
13841287200 = 2^5 * 3^2 * 5^2 * 13 * 19 * 43 * 181.
MATHEMATICA
Divisors[7^12 - 1]
PROG
(PARI) divisors(7^12-1)
(Sage) divisors(7^12-1)
(Magma) Divisors(7^12-1);
(Maxima) divisors(7^12-1);
CROSSREFS
Cf. Divisors of k^12-1: A003524 (k=2); A003532 (k=4); A003543 (k=8), A027902 (k=9), A027897 (k=10), A245028 (k=11).
Sequence in context: A225857 A168134 A245030 * A065108 A094563 A228897
KEYWORD
nonn,fini,full
AUTHOR
Bruno Berselli, Jul 10 2014
STATUS
approved