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

1,2

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

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 *)

Prog

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

Crossrefs

Cf. A067126.

Sequence in context: A233514 A096262 A308168 * A049646 A033556 A219044

Adjacent sequences: A193336 A193337 A193338 * A193340 A193341 A193342

Keyword

nonn

Author

M. F. Hasler, Jul 23 2011

Status

approved