A366955 a(n) is the Euler totient function of the concatenation of 1,2,3,...,n.

1, 4, 80, 616, 6576, 41088, 1224720, 4027392, 82260072, 4938271560, 635485074048, 41135376570624, 12236327748685824, 411522630337040436, 65843620853926470080, 6172839452588538935840, 805372326785629836739584, 40727551345036946357114880

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Formula

a(n) = phi(A007908(n)) = A000010(A007908(n)).

Crossrefs

Cf. A007908, A000010.

Sequence in context: A211152 A093854 A345459 * A269146 A192834 A054322

Adjacent sequences: A366952 A366953 A366954 * A366956 A366957 A366958

Keyword

nonn,base

Author

Sean A. Irvine, Oct 29 2023

Status

approved