

A090556


Beginning with 1, a(n) = least number m > a(n1) such that phi(a(n1)) divides phi(m).


2



1, 2, 3, 4, 5, 8, 10, 12, 13, 21, 26, 28, 35, 39, 45, 52, 56, 65, 97, 119, 153, 193, 221, 291, 357, 386, 388, 416, 442, 448, 476, 485, 579, 595, 663, 765, 769, 965, 1105, 1455, 1538, 1544, 1552, 1649, 1799, 2307, 2313, 2895, 3076, 3088, 3104, 3281, 3341, 3845, 4947
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


LINKS

Ivan Neretin, Table of n, a(n) for n = 1..308


FORMULA

a(1)=1, then a(n+1) = A069797(a(n)).  Ivan Neretin, May 01 2016


MATHEMATICA

NestList[Function[n, SelectFirst[Range[n + 1, 10^4], Divisible[EulerPhi@ #, EulerPhi@ n] &]], 1, 54] (* Michael De Vlieger, May 01 2016, Version 10 *)


CROSSREFS

Cf. A014573, A090557.
Sequence in context: A005233 A155736 A074897 * A223539 A332520 A211544
Adjacent sequences: A090553 A090554 A090555 * A090557 A090558 A090559


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Dec 10 2003


EXTENSIONS

Corrected and extended by Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 03 2004


STATUS

approved



