cp's OEIS Frontend

A060444 Table T(n,k) in which n-th row lists prime factors of 2^n + 1 (n >= 0), without repetition.

%I A060444 #27 Jun 29 2022 10:26:55
%S A060444 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,
%T A060444 3,11,331,65537,3,43691,5,13,37,109,3,174763,17,61681,3,43,5419,5,397,
%U A060444 2113,3,2796203,97,257,673,3,11,251,4051
%N A060444 Table T(n,k) in which n-th row lists prime factors of 2^n + 1 (n >= 0), without repetition.
%C A060444 Rows have irregular lengths.
%C A060444 The length of row n is A046799(n).
%D A060444 J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.
%H A060444 T. D. Noe, <a href="/A060444/b060444.txt">Rows n = 0..500 of triangle, flattened</a> (derived from Brillhart et al.)
%H A060444 J. Brillhart et al., <a href="http://dx.doi.org/10.1090/conm/022">Factorizations of b^n +- 1</a>, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
%H A060444 S. S. Wagstaff, Jr., <a href="http://www.cerias.purdue.edu/homes/ssw/cun/index.html">The Cunningham Project</a>.
%H A060444 Chai Wah Wu, <a href="https://github.com/postvakje/Reformatted-Cunningham-Project-tables">Tables from the Cunningham Project in machine-readable JSON format.</a>
%e A060444 Triangle begins:
%e A060444   2;
%e A060444   3;
%e A060444   5;
%e A060444   3,17;
%e A060444   3,11;
%e A060444   5,13;
%e A060444   3,43;
%e A060444   257;
%e A060444   ...
%t A060444 Flatten[Table[Transpose[FactorInteger[2^n+1]][[1]],{n,0,25}]] (* _Harvey P. Dale_, Aug 10 2011 *)
%o A060444 (PARI) apply( A060444_row(n)=factor(2^n+1)[,1]~, [0..10]) \\ _M. F. Hasler_, Nov 19 2018
%Y A060444 Cf. A001269 (factors with repetition), A046799 (number of prime divisors).
%K A060444 nonn,tabf
%O A060444 0,1
%A A060444 _N. J. A. Sloane_