A323615 - OEIS

%I #32 Dec 20 2024 20:43:08

%S 1,1,2,6,24,4,24,3,24,216,21,231,19,247,17,255,15,255,14,266,13,273,

%T 12,276,11,275,10,270,9,261,8,248,7,231,7854,224,8064,217,5,195,7800,

%U 190,7980,185,8140,180,8280,176,8448,172,8600,168,8736,164

%N a(0) = 1; for n > 0, a(n) = floor(a(n-1)/n) if positive and not already in the sequence, otherwise a(n) = a(n-1)*n.

%C Variation on A008336 using floor division and A076039 not allowing for values already in the sequence.

%H Jan Koornstra, <a href="/A323615/b323615.txt">Table of n, a(n) for n = 0..10000</a>

%e a(5) = 4, since floor(24/5) = 4, which is positive and not already in the sequence.

%e a(6) = 24, since floor(4/6) = 0, hence not positive.

%t Nest[Append[#1, If[And[#3 > 0, FreeQ[#1, #3]], #3, #2 #1[[-1]] ]] & @@ {#1, #2, Floor[#1[[-1]]/#2]} & @@ {#, Length@ #} &, {1}, 53] (* _Michael De Vlieger_, Jan 23 2019 *)

%o (Python)

%o def a323615(n):

%o   seq = []

%o   for i in range(n + 1):

%o     if i == 0: x = 1

%o     else:

%o       x = seq[i - 1] // i

%o       if x in seq or x == 0: x = seq[i - 1] * i

%o     seq.append(x)

%o   return seq

%o print(a323615(100))

%Y Cf. A008336, A076039.

%K nonn,easy,look

%O 0,3

%A _Jan Koornstra_, Jan 20 2019