A075882 a(n) = phi(Sum_{i=1,...,n} prime(i)).

1, 4, 4, 16, 12, 40, 28, 60, 40, 84, 64, 196, 96, 280, 160, 252, 160, 332, 280, 420, 352, 672, 396, 636, 416, 756, 624, 912, 576, 1044, 672, 1232, 840, 1416, 1136, 1616, 1152, 2640, 1380, 1764, 1540, 2292, 1696, 2552, 1872, 2816, 1896, 4524, 2208, 4032, 2120

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

The sum of the first three primes = 10 and phi(10) = 4, so a(3) = 4.

Mathematica

Table[EulerPhi[Sum[Prime[k], {k, 1, i}]], {i, 1, 100}]
EulerPhi[Accumulate[Prime[Range[60]]]] (* Harvey P. Dale, Jun 18 2024 *)

Crossrefs

Sequence in context: A273830 A250069 A333169 * A369891 A125757 A196065

Adjacent sequences: A075879 A075880 A075881 * A075883 A075884 A075885

Keyword

nonn

Author

Joseph L. Pe, Oct 16 2002

Status

approved