A257665 Totient of the n-th perfect number.

2, 12, 240, 4032, 16773120, 4294901760, 68719214592, 1152921503533105152, 1329227995784915871750885555673497600, 95780971304118053647396688887409314154826126411694080, 6582018229284824168619876730229320890292528855852623664389292032

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Formula

a(n) = A000010(A000396(n)).

Mathematica

Map[EulerPhi, (# (# + 1))/2 & /@ Select[2^Range[100] - 1, PrimeQ]] (* Michael De Vlieger, Jul 25 2015, after Harvey P. Dale at A000396 *)

Crossrefs

Cf. A000010, A000396, subsequence of A098203.

Sequence in context: A125804 A119700 A141083 * A132877 A007685 A132987

Adjacent sequences: A257662 A257663 A257664 * A257666 A257667 A257668

Keyword

nonn

Author

Carl Schildkraut, Jul 12 2015

Status

approved