A100390 Numbers n where A006530 has a local minimum.

4, 6, 8, 12, 16, 18, 20, 24, 27, 30, 32, 36, 40, 42, 45, 48, 50, 52, 54, 56, 60, 64, 66, 68, 70, 72, 75, 77, 81, 84, 88, 90, 96, 98, 100, 102, 105, 108, 110, 112, 114, 117, 120, 125, 128, 130, 132, 135, 138, 140, 144, 147, 150, 154, 156, 160, 162, 165, 168, 175, 180

Offset: 1

Author

Labos Elemer, Dec 14 2004

Keywords

• nonn

Comments

Powers of 2 and mostly largest powers of larger primes belong here.

Examples

			Let gpf(n) = A006530(n). 18 is in the sequence because gpf(17) = 17 > gpf(18) = 3 < gpf(19) = 19.
		

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A006530.

Programs

Mathematica

mxp[x_] := Max[FactorInteger[x][[All, 1]]]; ta = {{0}}; Do[s1 = mxp[n - 1]; s = mxp[n]; s2 = mxp[n + 1]; If[Greater[s1, s] && Greater[s2, s], Print[{n, {s1, s, s2}}]; ta = Append[ta, n]], {n, 1, 512}]; ta = Delete[ta, 1] (* Original program edited by Michael De Vlieger, Mar 26 2017 *)
With[{n = 181}, Select[MapIndexed[{First@ #2 + 1, Differences@ #1} &, Partition[Array[FactorInteger[#][[-1, 1]] &, n], 3, 1]], Apply[And[#1 < 0, #2 > 0] &, Last@ #] &][[All, 1]]] (* Michael De Vlieger, Mar 26 2017 *)

Formula

a(n) = A082418(n) + 1. - T. D. Noe, Nov 26 2007