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A076245 Numbers at which values of A051547 increase. 3
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 (list; graph; refs; listen; history; text; internal format)
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: A319899 A085493 A139252 * A318953 A172308 A190812

Adjacent sequences:  A076242 A076243 A076244 * A076246 A076247 A076248

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 08 2002

STATUS

approved

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Last modified December 8 18:37 EST 2019. Contains 329865 sequences. (Running on oeis4.)