The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A037101

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A037101

Trajectory of 3 under map n->7n+1 if n odd, n->n/2 if n even.
(history; published version)

#12 by Alois P. Heinz at Mon Mar 22 17:22:38 EDT 2021

STATUS

reviewed

approved

#11 by Michel Marcus at Mon Mar 22 15:50:08 EDT 2021

STATUS

proposed

reviewed

#10 by Michael S. Branicky at Mon Mar 22 15:47:27 EDT 2021

STATUS

editing

proposed

#9 by Michael S. Branicky at Mon Mar 22 15:47:08 EDT 2021

NAME

Trajectory of 3 under map n->7n+1 if n odd, n->n/2 if n even.

DATA

3, 22, 11, 78, 39, 274, 137, 960, 480, 240, 120, 60, 30, 15, 106, 53, 372, 186, 93, 652, 326, 163, 1142, 571, 3998, 1999, 13994, 6997, 48980, 24490, 12245, 85716, 42858, 21429, 150004, 75002, 37501, 262508, 131254, 65627, 459390, 229695, 1607866, 803933

PROG

(Python)

def iter(n): return 7*n+1 if n%2 == 1 else n//2

def aupton(terms):

alst = [3]

for n in range(1, terms+1): alst.append(iter(alst[-1]))

return alst

print(aupton(43)) # Michael S. Branicky, Mar 22 2021

CROSSREFS

Cf. A063871.

STATUS

approved

editing

#8 by Bruno Berselli at Fri Jan 24 12:14:03 EST 2020

STATUS

proposed

approved

#7 by Robert Israel at Fri Jan 24 11:56:39 EST 2020

STATUS

editing

proposed

#6 by Robert Israel at Fri Jan 24 11:56:32 EST 2020

LINKS

Robert Israel, <a href="/A037101/b037101.txt">Table of n, a(n) for n = 0..10000</a>

MAPLE

a:= proc(n) option remember; local v;

v:= procname(n-1);

if v::odd then 7*v+1 else v/2 fi

end proc:

a(0):= 3:

map(a, [$0..100]); # Robert Israel, Jan 24 2020

STATUS

approved

editing

#5 by Harvey P. Dale at Tue Jun 05 19:10:11 EDT 2012

STATUS

editing

approved

#4 by Harvey P. Dale at Tue Jun 05 19:10:02 EDT 2012

MATHEMATICA

nxt[n_]:=If[OddQ[n], 7n+1, n/2]; NestList[nxt, 3, 40] (* Harvey P. Dale, Jun 05 2012 *)

STATUS

approved

editing

#3 by Russ Cox at Fri Mar 30 16:47:44 EDT 2012

AUTHOR

_N. J. A. Sloane (njas(AT)research.att.com)_.

Discussion

Fri Mar 30

16:47

OEIS Server: https://oeis.org/edit/global/110