OFFSET
1,2
COMMENTS
Every k >= 1 appears in this sequence exactly A330128(k) times. So there are 2137453 1's, 194697747222394 2's, 2 3's, 209534289952018960 6's, and so on.
a(n) is the most remote ancestor of n in the comma-successor graph.
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..10000
Eric Angelini, Michael S. Branicky, Giovanni Resta, N. J. A. Sloane, and David W. Wilson, The Comma Sequence: A Simple Sequence With Bizarre Properties, arXiv:2401.14346, Youtube
EXAMPLE
PROG
(Python)
def comma_predecessor(n): # A367614(n)
y = int(str(n)[0])
x = (n-y)%10
k = n - y - 10*x
kk = k + 10*x + y-1
return k if k > 0 and int(str(kk)[0]) != y-1 else -1
def a(n):
an = n
while (cp:=comma_predecessor(an)) > 0: an = cp
return an
print([a(n) for n in range(1, 76)]) # Michael S. Branicky, Dec 18 2023
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Dec 05 2023
STATUS
approved