A076245 Numbers at which values of A051547 increase.

1, 3, 5, 7, 11, 15, 17, 19, 23, 29, 47, 51, 53, 59, 81, 83, 85, 101, 103, 107, 149, 163, 167, 173, 179, 191, 197, 227, 251, 255, 257, 263, 269, 283, 293, 311, 317, 347, 359, 367, 383, 389, 467, 479, 487, 503, 509, 557, 563, 569, 587, 607, 619, 643, 653, 677

Offset

1,2

Comments

Observe that both primes and composites (including 15, 51, 81, 85, and 255) occur.

In totients of consecutive terms some prime-factor appears at higher power than in preceding ones: see A076246 and A051451.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..13256 (First 1924 terms from Vincenzo Librandi; a(n) <= 10^6.)

Mathematica

With[{s = FoldList[LCM @@ {#1, EulerPhi@ #2} &, Range[700]]}, Map[FirstPosition[s, #][[1]] &, Union@ FoldList[Max, s]]] (* Michael De Vlieger, Dec 09 2018 *)

Prog

(PARI) lista(nn) = {least = 1; print1(1, ", "); for (n=2, nn, nleast = lcm(least, eulerphi(n)); if (nleast > least, print1(n, ", ")); least = nleast; ); } \\ Michel Marcus, Jul 30 2017

Crossrefs

Cf. A003418, A051451, A051547, A076244.

Sequence in context: A085493 A343621 A139252 * A370647 A318953 A172308

Adjacent sequences: A076242 A076243 A076244 * A076246 A076247 A076248

Keyword

nonn

Author

Labos Elemer, Oct 08 2002

Status

approved