A280707 Collatz-2 (A063041) trajectory starting at 47.

47, 2022, 1011, 337, 111548, 55774, 27887, 353, 123198, 61599, 20533, 421357694, 210678847, 44385566460664754, 22192783230332377, 1707137171564029, 165918667661, 27529004277737692540278, 13764502138868846270139, 4588167379622948756713, 352935952278688365901, 3237944516318241889, 1577861856421, 2489648037916767181800822

Offset: 0

Author

Antti Karttunen, Jan 23 2017

Keywords

• nonn

Comments

Will this sequence ever settle into a finite cycle?

Links

• Sean A. Irvine, Table of n, a(n) for n = 0..134 (terms 0..41 from Antti Karttunen, terms 42..103 from Hans Havermann)

Crossrefs

Cf. A032742, A063041, A063045, A063046.

Programs

PARI

A032742(n) = if(1==n,n,n/vecmin(factor(n)[,1]));
A063041(n) = if(2==n,3,if(isprime(n),1+(precprime(n-1)*n),A032742(n)));
n = 0; k = 47; while(n <= 41, write("b280707.txt", n, " ", k); k = A063041(k); n = n+1);

Formula

a(0) = 47 and for n > 1, a(n) = A063041(a(n-1)).