cp's OEIS Frontend

A333053 Numbers m such that min(d(m), d(m+1)) > min(d(k), d(k+1)) for all k < m, where d(m) is the number of divisors of m (A000005).

%I A333053 #4 Mar 06 2020 22:40:19
%S A333053 1,2,8,14,44,104,224,495,735,2024,2079,5264,5984,21735,126224,201824,
%T A333053 862784,1890944,2821455,6116175,7316000,14753024,23014719,38127375,
%U A333053 80061344,205466624,391738599,879207615,1794220064,3199900599,3809727999,16916370624
%N A333053 Numbers m such that min(d(m), d(m+1)) > min(d(k), d(k+1)) for all k < m, where d(m) is the number of divisors of m (A000005).
%C A333053 The corresponding values of min(d(a(n)), d(a(n)+1)) are 1, 2, 3, 4, 6, 8, 9, 10, 12, 15, 16, 20, 24, 32, 40, 48, 56, 64, 72, 80, 96, 108, 112, 120, 144, 160, 192, 224, 240, 256, 288, 320, ...
%e A333053 The values of min(d(k), d(k+1)) for k = 1, 2, ... 8 are 1, 2, 2, 2, 2, 2, 2, 3. The record values in this range, 1, 2 and 3, are obtained at k = 1, 2, and 8.
%t A333053 seq={}; dminmax = 0; d1 = 1; Do[d2 = DivisorSigma[0, n];dmin = Min[d1, d2]; If[dmin > dminmax, dminmax = dmin; AppendTo[seq, n-1]]; d1 = d2, {n, 2, 10^6}]; seq
%Y A333053 Cf. A000005, A002182, A123000, A175143, A333054.
%K A333053 nonn,more
%O A333053 1,2
%A A333053 _Amiram Eldar_, Mar 06 2020