A245027 -id:A245027 - cp's OEIS frontend

A245028 Divisors of 11^12 - 1.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 18, 19, 20, 21, 24, 26, 28, 30, 35, 36, 37, 38, 39, 40, 42, 45, 48, 52, 56, 57, 60, 61, 63, 65, 70, 72, 74, 76, 78, 80, 84, 90, 91, 95, 104, 105, 111, 112, 114, 117, 120, 122, 126, 130, 133, 140, 144, 148, 152

Offset: 1

Bruno Berselli, Jul 10 2014

See Comments section in A245027.
The following 36 triangular numbers belong to this sequence: 1, 3, 6, 10, 15, 21, 28, 36, 45, 78, 91, 105, 120, 171, 190, 210, 630, 666, 703, 741, 780, 1596, 1830, 4095, 4560, 5460, 6216, 16653, 33670, 46360, 103740, 115440, 221445, 274170, 365085, 392303547090.
The following terms of A001082 (without 1, 21 and 120, which appear in the previous list) are in sequence: 5, 8, 16, 40, 56, 65, 133, 208, 280, 456, 481, 560, 936, 1008, 1281, 1365, 1680, 1776, 1976, 4880, 5985, 10920, 11285, 44408, 47880, 590520, 658008, 731120, 973560, 1046142792240.
Also, 4/5 of the members are divisible by 3 and 2/3 of them are even.

			3138428376720 = 2^4 * 3^2 * 5 * 7 * 13 * 19 * 37 * 61 * 1117.

Bruno Berselli, Table of n, a(n) for n = 1..1920
Index entries for sequences related to divisors of numbers

Cf. Divisors of k^12-1: A003524 (k=2); A003532 (k=4); A245027 (k=7), A003543 (k=8), A027902 (k=9), A027897 (k=10).

Magma
```
Divisors(11^12-1);
```
Mathematica
```
Divisors[11^12 - 1]
```
Maxima
```
divisors(11^12-1);
```
PARI
```
divisors(11^12-1)
```
Sage
```
divisors(11^12-1)
```

A245030 Divisors of 7^24 - 1.

Original entry on oeis.org

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, 64, 65, 72, 73, 75, 76, 78, 80, 86, 90, 95, 96, 100, 104, 114, 117, 120, 129, 130, 144, 146, 150, 152, 156, 160, 171, 172, 180, 181, 190

Offset: 1

Bruno Berselli, Jul 10 2014

Number of divisors of k^24-1 for k = 2..10: 96 (2), 384 (3), 768 (4), 1152 (5), 512 (6), 16128 (7), 8192 (8), 14336 (9), 2048 (10).
The following 36 triangular numbers belong to this sequence: 1, 3, 6, 10, 15, 36, 45, 78, 120, 171, 190, 300, 325, 741, 780, 2080, 2628, 2850, 4560, 8256, 8385, 14706, 16290, 18528, 74691, 170820, 334153, 450775, 720600, 1664400, 4191960, 5915080, 8654880, 19068400, 1730160900, 23947653922570801800.
There are 50 divisors a(k) such that a(k) is divisible by k.
Sum( A000005(a(i))^3, i=1..16128 ) = sum( A000005(a(i)), i=1..16128 )^2, see Kordemsky in References and Barbeau et al. in Links section.

			191581231380566414400 = 2^6*3^2*5^2*13*19*43*73*181*193*409*1201.

Boris A. Kordemsky, The Moscow Puzzles: 359 Mathematical Recreations, C. Scribner's Sons (1972), Chapter XIII, Paragraph 349.

Michael De Vlieger, Table of n, a(n) for n = 1..16128
Edward Barbeau and Samer Seraj, Sum of Cubes is Square of Sum, arXiv:1306.5257 [math.NT]
Index entries for sequences related to divisors of numbers

Cf. A000005, A158649, A245027.

Mathematica
```
Divisors[7^24 - 1]
```
PARI
```
divisors(7^24-1)
```

cp's OEIS Frontend

A245028 Divisors of 11^12 - 1.

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