OFFSET
0,2
COMMENTS
LINKS
Paul Pollack, Carl Pomerance, and Enrique Treviño, Sets of monotonicity for Euler's totient function, preprint. See M(n).
Paul Pollack, Carl Pomerance, and Enrique Treviño, Sets of monotonicity for Euler's totient function, Ramanujan J. 30 (2013), no. 3, pp. 379-398.
Terence Tao, Monotone non-decreasing sequences of the Euler totient function, arXiv:2309.02325 [math.NT], 2023.
FORMULA
a(n) = A006880(n)+64 for n >= 5 (conjectured).
PROG
(Python)
from bisect import bisect
from sympy import totient
def A365474(n):
m = 10**n
plist, qlist, c = tuple(totient(i) for i in range(1, m+1)), [0]*(m+1), 0
for i in range(m):
qlist[a:=bisect(qlist, plist[i], lo=1, hi=c+1, key=lambda x:plist[x])]=i
c = max(c, a)
return c
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Chai Wah Wu, Sep 04 2023
STATUS
approved