cp's OEIS Frontend

A326791 For n > 1, let f_n be the lexicographically earliest sequence of distinct positive terms such that f_n(1) = 1, f_n(2) = n, and for k > 2, f_n(k) divides f_n(k-2) + f_n(k-1); if f_n is finite, then a(n) is the number of terms of f_n, otherwise a(n) = -1; a(1) = 1.

%I A326791 #10 Oct 21 2019 19:29:18
%S A326791 1,39,23,5,10,9,31,8,8,8,7,8,7,9,10,29,9,38,36,13,14,13,8,12,40,19,11,
%T A326791 25,10,15,13,18,11,5,39,36,40,37,12,25,11,12,29,30,33,25,32,5,40,25,
%U A326791 12,25,11,21,40,27,18,19,17,9,41,18,11,5,41,37,40,12,29
%N A326791 For n > 1, let f_n be the lexicographically earliest sequence of distinct positive terms such that f_n(1) = 1, f_n(2) = n, and for k > 2, f_n(k) divides f_n(k-2) + f_n(k-1); if f_n is finite, then a(n) is the number of terms of f_n, otherwise a(n) = -1; a(1) = 1.
%C A326791 Apparently, f_n is finite for any n > 0.
%C A326791 The first records are:
%C A326791   n        a(n)
%C A326791   -------  ----
%C A326791         1     1
%C A326791         2    39
%C A326791        25    40
%C A326791        61    41
%C A326791        78    45
%C A326791       266    47
%C A326791       279    56
%C A326791       629   102
%C A326791     95417   103
%C A326791    331468   104
%C A326791   1318090   108
%C A326791   5383290   109
%H A326791 Rémy Sigrist, <a href="/A326791/a326791.gp.txt">PARI program for A326791</a>
%e A326791 For n = 2:
%e A326791 - f_2 corresponds to A085947 which is finite with 39 terms,
%e A326791 - hence a(2) = 39.
%o A326791 (PARI) See Links section.
%Y A326791 Cf. A085947.
%K A326791 nonn
%O A326791 1,2
%A A326791 _Rémy Sigrist_, Oct 19 2019