login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A060444 Table T(n,k) in which n-th row lists prime factors of 2^n + 1 (n >= 0), without repetition. 4
2, 3, 5, 3, 17, 3, 11, 5, 13, 3, 43, 257, 3, 19, 5, 41, 3, 683, 17, 241, 3, 2731, 5, 29, 113, 3, 11, 331, 65537, 3, 43691, 5, 13, 37, 109, 3, 174763, 17, 61681, 3, 43, 5419, 5, 397, 2113, 3, 2796203, 97, 257, 673, 3, 11, 251, 4051 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Rows have irregular lengths.

The length of row n is A046799(n).

REFERENCES

J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.

LINKS

T. D. Noe, Rows n = 0..500 of triangle, flattened (derived from Brillhart et al.)

J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.

S. S. Wagstaff, Jr., The Cunningham Project.

EXAMPLE

2; 3; 5; 3,17; 3,11; 5,13; 3,43; 257; ...

MATHEMATICA

Flatten[Table[Transpose[FactorInteger[2^n+1]][[1]], {n, 0, 25}]] (* Harvey P. Dale, Aug 10 2011 *)

PROG

(PARI) apply( A060444_row(n)=factor(2^n+1)[, 1]~, [0..10]) \\ M. F. Hasler, Nov 19 2018

CROSSREFS

Cf. A001269 (factors with repetition), A046799 (number of prime divisors).

Sequence in context: A244609 A209195 A113222 * A002587 A152814 A280319

Adjacent sequences:  A060441 A060442 A060443 * A060445 A060446 A060447

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 7 02:39 EDT 2020. Contains 333292 sequences. (Running on oeis4.)