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

1,1

Comments

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

Links

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

Formula

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

Example

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

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 *)

Crossrefs

Cf. A006530.

Sequence in context: A310662 A231569 A337812 * A199768 A157932 A097619

Adjacent sequences: A100387 A100388 A100389 * A100391 A100392 A100393

Keyword

nonn

Author

Labos Elemer, Dec 14 2004

Status

approved