OFFSET
0,4
COMMENTS
LINKS
Markus Sigg, Table of n, a(n) for n = 0..93
EXAMPLE
For n=5, the positive integers which need <= 5 Collatz steps to reach 1 and the a(5) = 4 gaps between runs in them are
1,2, 4,5, 8, 16, 32
gaps ^ ^ ^ ^
PROG
(Python)
def printUpTo(n):
L = [ 1 ]
T = [ 1 ]
print("0 0")
for i in range(1, n + 1):
L = [2*x for x in L] + [(x-1) // 3 for x in L if x > 4 and x % 6 == 4]
T = T + L
T.sort()
print(i, sum(1 for i in range(1, len(T)) if T[i - 1] < T[i] - 1))
printUpTo(48)
CROSSREFS
KEYWORD
nonn
AUTHOR
Markus Sigg, Dec 19 2025
STATUS
approved