A193339 Indices of record values in A001783.

1, 3, 4, 5, 7, 9, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241

Offset: 1

Author

M. F. Hasler, Jul 23 2011

Keywords

• nonn

Comments

Indices k such that A001783(k) is larger than all preceding terms of that sequence. The corresponding values A001783(k) are given in A193338.

It appears that, except for 1, 2, 4, and 9, this is all and only the primes. (It certainly includes all odd primes.) - Franklin T. Adams-Watters, Aug 11 2011

It appears that this is the sequence of indices of records in A206369. - Michel Marcus, Nov 04 2017

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A067126.

Programs

Mathematica

Block[{s = Table[Times @@ Select[Range@ n, CoprimeQ[n, #] &], {n, 250}], t}, t = Union@ FoldList[Max, s]; Map[FirstPosition[s, #][[1]] &, t]] (* or *)
Union[Prime@ Range[2, 53], Range[3]^2] (* Michael De Vlieger, Nov 04 2017 *)

PARI

m=0;for(n=1,599,m+0<(m=max(m,A001783(n))) & print1(n", "))