This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A346161 #28 Aug 22 2021 22:14:50 %S A346161 2,3,7,23,47,191,383,1439,2879,11519,23039,261071,1044287,2949119, %T A346161 31426559,194224127,1069493759,8554807007,31337349119,68438456063, %U A346161 136876912127,547507648511,8760122376191 %N A346161 Prime numbers p such that the number of iterations of map A039634 required for p to reach 2 sets a new record. %C A346161 It seems that the record number of iterations for a(n) is n-1. %C A346161 Alternatively, prime numbers p such that the number of odd primes encountered under iteration of A004526 sets a new record. - _Martin Ehrenstein_, Aug 16 2021 %e A346161 Terms in this sequence are indicated in square brackets in the tree below for primes up to 97. Note that a(n) is the smallest prime of depth n-1. %e A346161 1 ___________[2]____________ %e A346161 | / / | \ \ \ %e A346161 _______[3]__ ____ 5 _ 17 19 37 67 73 %e A346161 / | \ / | \ | | %e A346161 _[7]_ 13 97 11 41 43 71 79 %e A346161 / | \ | / \ | %e A346161 29 31 61 53 [23] 89 83 %e A346161 | | %e A346161 59 [47] %o A346161 (Python) %o A346161 from sympy import nextprime, isprime %o A346161 rec = -1; p1 = 1 %o A346161 while p1 < 1000000000: %o A346161 p = nextprime(p1); m = p; ct = 0 %o A346161 while m > 2: %o A346161 if isprime(m): ct += 1 %o A346161 m //= 2 %o A346161 if ct > rec: print(p); rec = ct %o A346161 p1 = p %Y A346161 Cf. A005384, A058000, A039634, A346063, A346163. %K A346161 nonn,more %O A346161 1,1 %A A346161 _Ya-Ping Lu_, Jul 08 2021 %E A346161 a(19)-a(23) from _Martin Ehrenstein_, Aug 22 2021