A166156 - OEIS

A166156

Numbers k such that phi(k) = number of perfect partitions of (k-1).

1, 2, 4, 8, 16, 20, 32, 64, 112, 128, 256, 512, 1024, 2048, 2816, 4096, 8192, 13312, 16384, 32768, 65536, 131072, 262144, 278528, 524288, 1000512, 1048576, 1245184, 2097152, 4194304, 8388608, 16777216, 24117248, 33554432, 67108864

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OFFSET

1,2

COMMENTS

Numbers k such that A000010(k) = A002033(k-1).

Also numbers k such that A000010(k) = A074206(k). - Amiram Eldar, Feb 29 2020

LINKS

Table of n, a(n) for n=1..35.

MATHEMATICA

f[1] = 1; f[n_] := f[n] = Plus @@ (f /@ Most @ Divisors[n]); Select[Range[1000], f[#] == EulerPhi[#] &] (* Amiram Eldar, Feb 29 2020 *)

CROSSREFS

Cf. A000010, A002033, A074206.

A000079 is a subsequence.

Sequence in context: A125508 A067945 A309263 * A089473 A118021 A326312

Adjacent sequences: A166153 A166154 A166155 * A166157 A166158 A166159

KEYWORD

nonn,more

AUTHOR

Juri-Stepan Gerasimov, Oct 08 2009

EXTENSIONS

Index in the definition corrected, and extended by R. J. Mathar, Oct 10 2009

a(18)-a(35) from Amiram Eldar, Feb 29 2020

STATUS

approved