cp's OEIS Frontend

A058973 First integer reached in A058972.

%I A058973 #14 Feb 09 2022 09:05:02
%S A058973 1,2,3,2,4,2,5,9,2,4,8,8,9,9,10,8,8,11,2,2,12,2,13,13,14,15,4,16,2,17,
%T A058973 4,35,19,8,23,9,8,22,25,2,26,25,2,2,24,28,8,10,4,29,2,26,29,2,2,35,33,
%U A058973 6,2,38,33,33,40,2,68,4,8,44,41,8,4,46,35,43,49,50,2,42,8,40,58,4,59,43,61
%N A058973 First integer reached in A058972.
%H A058973 P. Schogt, <a href="http://arxiv.org/abs/1211.6583">The Wild Number Problem: math or fiction?</a>, arXiv preprint arXiv:1211.6583 [math.HO], 2012. - From _N. J. A. Sloane_, Jan 03 2013
%e A058973 A058972(1) = 3: f(3/1) = 3/3 = 1 = a(1);
%e A058973 A058972(2) = 9: f(9/1) = 8/4 = 2 = a(2);
%e A058973 A058972(3) = 15: f(15/1) = 15/5 = 3 = a(3);
%e A058973 A058972(4) = 24: f(24/1) = 6/3 = 2 = a(4).
%o A058973 (PARI) f2(p,q) = (sigma(p+q)-p-q)/numdiv(p+q);
%o A058973 f1(r) = f2(numerator(r), denominator(r));
%o A058973 loop(list) = {my(v=Vecrev(list)); for (i=2, #v, if (v[i] == v[1], return(1)););}
%o A058973 ff(n) = {my(ok=0, m=f2(n,1), list=List()); while(denominator(m) != 1, m = f1(m); listput(list, m); if (loop(list), return (0));); return(m);}
%o A058973 lista(nn) = {for (n=1, nn, my(x=ff(n)); if (x, print1(x, ", ")););} \\ _Michel Marcus_, Feb 09 2022
%Y A058973 Cf. A058972.
%K A058973 nonn,easy
%O A058973 1,2
%A A058973 _N. J. A. Sloane_, Jan 14 2001
%E A058973 Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 22 2003