A186259 a(n) = 7*b_7(n) + 6, where b_7 lists the indices of zeros of the sequence u(n) = abs(u(n-1) - gcd(u(n-1), 7n-1)), u(1) = 1.
20, 167, 797, 6299, 48817, 389437, 3114313, 24910031, 199280101, 1594149787, 12752862247, 102022886167, 816183074713, 6529464593329, 52235716720753, 417885733765933, 3343085868722137, 26744686949777089, 213957495598165381, 1711659964119801373
Offset: 1
Keywords
Links
- B. Cloitre, 10 conjectures in additive number theory, preprint arxiv:2011.4274 (2011).
- M. F. Hasler, Rowland-Cloître type prime generating sequences, OEIS Wiki, August 2015.
Programs
-
PARI
a=1; m=7; for(n=2, 1e7, a=abs(a-gcd(a, m*n-1)); if(a==0, print1(m*n+m-1, ", ")))
-
PARI
m=7; a=k=1; for(n=1, 20, while( a>D=vecmin(apply(p->a%p, factor(N=m*(k+a)+m-1)[, 1])), a-=D+gcd(a-D, N); k+=1+D); k+=a+1; print1(a=N, ", ")) \\ M. F. Hasler, Aug 22 2015
Formula
We conjecture that a(n) is asymptotic to c*8^n with c>0.
See the wiki link for a sketch of a proof of this conjecture. We find c = 1.48462836... - M. F. Hasler, Aug 22 2015
Extensions
Edited by M. F. Hasler, Aug 14 2015
More terms from M. F. Hasler, Aug 22 2015
Comments