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A189057

Numbers n for which phi(n)=sigma(n'), where phi is the Euler totient function, sigma is the sum of divisors and n' the arithmetic derivative of n.

2, 57, 175, 357, 381, 543, 777, 903, 2379, 3027, 6807, 25823, 47047, 74333, 82621, 136213, 153425, 163471, 194873, 230547, 257799, 259555, 265111, 269545, 285439, 289009, 302403, 305305, 311395, 354365, 416005, 484169, 569245, 718333, 755885, 781501, 1012505

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OFFSET

1,1

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..300

EXAMPLE

phi(57)=36. 57'=22 and sigma(22)=36

phi(1012505)=725760. 1012505'=310156 and sigma(310156)=725760

MAPLE

with(numtheory);

P:=proc(i)

local f, n, p, pfs;