login
A362372
Inventory of powers. Initialize the sequence with '1'. Then record the number of powers of 1 thus far, then do the same for powers of 2 (2, 4, 8, ...), powers of 3, etc. When the count is zero, do not record a zero; rather start the inventory again with the powers of 1.
1
1, 1, 2, 1, 3, 1, 1, 5, 1, 1, 7, 1, 1, 9, 1, 2, 10, 2, 2, 10, 4, 2, 1, 1, 12, 6, 2, 1, 1, 1, 1, 16, 8, 2, 2, 1, 1, 1, 1, 1, 2, 21, 12, 2, 2, 1, 1, 1, 1, 1, 2, 26, 15, 2, 2, 1, 1, 1, 1, 1, 2, 31, 18, 2, 2, 1, 1, 1, 1, 1, 2, 36, 21, 2, 2, 1, 2, 1, 1, 1
OFFSET
0,3
COMMENTS
A variant of the inventory sequence, A342585.
The graph exhibits sharp jumps followed by a rapid decline forming a periodic hockey stick pattern. Larger-scale, near-linear structures also appear.
Periodic patterns in the relative frequency of any given number also are present. For example, perform a rolling count of the number of times 2 appears in the previous 40 entries.
Open question: will all positive integers appear in the sequence?
LINKS
Michael S. Branicky, Table of n, a(n) for n = 0..10000 (first 4330 terms from Damon Lay)
EXAMPLE
As an irregular triangle, the table begins:
1;
1;
2, 1;
3, 1, 1;
5, 1, 1;
7, 1, 1;
9, 1, 2;
10, 2, 2;
10, 4, 2, 1, 1;
12, 6, 2, 1, 1, 1, 1;
16, 8, 2, 2, 1, 1, 1, 1, 1, 2;
...
Initialize the sequence with '1'.
Powers of 1 are counted in the first column, powers of 2 in the second, powers of 3 in the third, etc.
PROG
(Python)
from collections import Counter
from sympy import divisors, perfect_power
def powers_in(n):
t = perfect_power(n) # False for n == 1
return [n] if not t else [t[0]**d for d in divisors(t[1])]
def aupton(nn):
num, alst, inventory = 1, [1], Counter([1])
while len(alst) <= nn:
c = inventory[num]
if c == 0: num = 1
else: num += 1; alst.append(c); inventory.update(powers_in(c))
return alst
print(aupton(100)) # Michael S. Branicky, May 05 2023
CROSSREFS
Cf. A342585 and similar variants thereof: A345730, A347791, A348218, A352799, A353092.
Sequence in context: A141412 A178623 A210765 * A160183 A168534 A026807
KEYWORD
easy,nonn,tabf
AUTHOR
Damon Lay, Apr 17 2023
STATUS
approved