A250210 Irregular triangle read by rows in which row n lists the prime factors of the duodecimal repunit ((12^n-1)/11). (Written in base 10)

13, 157, 5, 13, 29, 22621, 7, 13, 19, 157, 659, 4943, 5, 13, 29, 89, 233, 37, 157, 80749, 13, 19141, 22621, 11, 23, 266981089, 5, 7, 13, 19, 29, 157, 20593, 477517, 20369233, 13, 211, 659, 4943, 13063, 61, 157, 661, 9781, 22621, 5, 13, 17, 29, 89, 97, 233, 260753

Offset

2,1

Links

Table of n, a(n) for n=2..54.

Example

Triangle begins:
[13]
[157]
[5, 13, 29]
[22621]
[7, 13, 19, 157]
[659, 4943]
[5, 13, 29, 89, 233]
[37, 157, 80749]
[13, 19141, 22621]
...

Prog

(PARI) tabf(nn) = for (n=1, nn, print(factor((12^n-1)/11)[, 1]~); ); \\ Michel Marcus, Dec 29 2014

Crossrefs

Cf. A102380, A004064, A250288.

Sequence in context: A170694 A170732 A360172 * A142104 A140020 A130868

Adjacent sequences: A250207 A250208 A250209 * A250211 A250212 A250213

Keyword

nonn,tabf

Author

Eric Chen, Dec 29 2014

Status

approved