A349228 - OEIS

%I #11 Nov 18 2021 02:41:25

%S 1,2,4,8,12,6,3,5,10,20,16,24,36,9,15,25,50,30,18,27,45,60,40,32,48,

%T 72,54,63,21,7,11,22,44,28,14,35,55,110,66,42,84,56,64,80,120,75,90,

%U 150,180,210,126,105,135,225,270,240,96,112,70,140,100,160,200

%N Products of three consecutive terms of A349227: a(n) = A349227(n) * A349227(n+1) * A349227(n+2).

%C All terms are distinct.

%C Is this sequence a permutation of the natural numbers?

%H Rémy Sigrist, <a href="/A349228/b349228.txt">Table of n, a(n) for n = 1..10000</a>

%e a(5) = A349227(5) * A349227(6) * A349227(7) = 2 * 2 * 3 = 12.

%o (PARI) s=0; pp=p=1; for (n=1, 63, for (v=1, oo, if (!bittest(s, q=pp*p*v), print1 (q", "); s+=2^q; pp=p; p=v; break)))

%o (Python)

%o def aupton(terms):

%o     A349227lst, plst, pset = [1, 1], [], set()

%o     for n in range(terms):

%o         p = p2 = A349227lst[-1]*A349227lst[-2]

%o         while p in pset: p += p2

%o         A349227lst.append(p//p2); plst.append(p); pset.add(p)

%o     return plst

%o print(aupton(63)) # _Michael S. Branicky_, Nov 12 2021

%Y Cf. A088177, A349227.

%K nonn

%O 1,2

%A _Rémy Sigrist_, Nov 11 2021