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A365738
a(n) = A365737(10^n).
3
1, 3, 12, 32, 92, 292, 995, 3029, 9651, 31817
OFFSET
0,2
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, 379--398.
Terence Tao, Monotone non-decreasing sequences of the Euler totient function, arXiv:2309.02325 [math.NT], 2023.
PROG
(Python)
from bisect import bisect
from sympy import totient
def A365738(n):
k = 10**n
plist, qlist, c = tuple(-totient(i) for i in range(1, k+1)), [0]*(k+1), 0
for i in range(k):
qlist[a:=bisect(qlist, plist[i], lo=1, hi=c+1, key=lambda x:plist[x])]=i
c = max(c, a)
return c
KEYWORD
nonn,hard,more
AUTHOR
Chai Wah Wu, Sep 17 2023
EXTENSIONS
a(9) from Chai Wah Wu, Oct 13 2023
STATUS
approved