A365738 a(n) = A365737(10^n).

1, 3, 12, 32, 92, 292, 995, 3029, 9651, 31817

Offset

0,2

Links

Table of n, a(n) for n=0..9.

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

Crossrefs

Cf. A000010, A000720.

Cf. A365398, A365399, A365400, A365474, A365737, A365740, A365741, A061070.

Sequence in context: A098500 A037236 A309693 * A288605 A268768 A174963

Adjacent sequences: A365735 A365736 A365737 * A365739 A365740 A365741

Keyword

nonn,hard,more

Author

Chai Wah Wu, Sep 17 2023

Extensions

a(9) from Chai Wah Wu, Oct 13 2023

Status

approved