A260867 Least k > 1 that divides A260868(n) + 2^k - 2.

35, 161, 55, 35, 115, 35, 115, 35, 77, 209, 473, 253, 55, 77, 35, 235, 247, 55, 35, 35, 899, 119, 1003, 415, 143, 35, 335, 95, 299, 497, 203, 575, 35, 247, 323, 95, 77, 437, 901, 35, 55, 473, 35, 1457, 77, 55, 517, 35, 235, 493, 161, 535, 209, 115, 95, 1067, 689, 323, 35, 1199, 1313, 355, 77, 815, 635, 869, 235, 119, 551, 55, 115

Offset: 1

Author

M. F. Hasler, Aug 11 2015

Keywords

• nonn

Comments

For all numbers N not listed in A260868, the least k > 1 that divides N + 2^k - 2 is equal to the least prime factor of N.

It appears that the range of this sequence is A267999. For example, 155 occurs first somewhat late for N = 2729. - Corrected by Thomas Ordowski, Oct 27 2018

Programs

PARI

my(aa(n)=for(k=2,9e9,Mod(2,k)^k+n-2||return(k)));for(n=2,1e5,aa(n)==factor(n)[1,1]||print1(aa(n)","))