This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A365474 #28 Sep 04 2025 10:52:43 %S A365474 1,7,34,193,1276,9656,78562,664643,5761519,50847598 %N A365474 a(n) = A365339(10^n). %C A365474 The Pollack et al. reference lists a(4)-a(7) and conjectures that A365339(n) = A000720(n)+64 for n >= 31957 which in turn implies the conjecture that a(n) = A006880(n)+64 for n >= 5. %H A365474 Thomas Bloom, <a href="https://www.erdosproblems.com/49">Problem 49</a>, Erdős Problems. %H A365474 Paul Pollack, Carl Pomerance, and Enrique Treviño, <a href="https://math.dartmouth.edu/~carlp/MonotonePhi.pdf">Sets of monotonicity for Euler's totient function</a>, preprint. See M(n). %H A365474 Paul Pollack, Carl Pomerance, and Enrique Treviño, <a href="https://doi.org/10.1007/s11139-012-9386-6">Sets of monotonicity for Euler's totient function</a>, Ramanujan J. 30 (2013), no. 3, pp. 379-398. %H A365474 Terence Tao, <a href="https://arxiv.org/abs/2309.02325">Monotone non-decreasing sequences of the Euler totient function</a>, arXiv:2309.02325 [math.NT], 2023. %H A365474 Terence Tao, <a href="https://github.com/teorth/erdosproblems/blob/main/README.md#table">Erdős problem database</a>, see no. 49. %F A365474 a(n) = A006880(n)+64 for n >= 5 (conjectured). %o A365474 (Python) %o A365474 from bisect import bisect %o A365474 from sympy import totient %o A365474 def A365474(n): %o A365474 m = 10**n %o A365474 plist, qlist, c = tuple(totient(i) for i in range(1,m+1)), [0]*(m+1), 0 %o A365474 for i in range(m): %o A365474 qlist[a:=bisect(qlist,plist[i],lo=1,hi=c+1,key=lambda x:plist[x])]=i %o A365474 c = max(c,a) %o A365474 return c %Y A365474 Cf. A000010, A000720, A006880, A365339. %K A365474 nonn,hard,more,changed %O A365474 0,2 %A A365474 _Chai Wah Wu_, Sep 04 2023