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).

1, 2, 8, 14, 44, 104, 224, 495, 735, 2024, 2079, 5264, 5984, 21735, 126224, 201824, 862784, 1890944, 2821455, 6116175, 7316000, 14753024, 23014719, 38127375, 80061344, 205466624, 391738599, 879207615, 1794220064, 3199900599, 3809727999, 16916370624

Offset: 1

Author

Amiram Eldar, Mar 06 2020

Keywords

• nonn
• more

Comments

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, ...

Examples

			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.
		

Crossrefs

Cf. A000005, A002182, A123000, A175143, A333054.

Programs

Mathematica

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