(Scheme) (define (A169813 n) (A003987bi n (A000203 n))) ;; Where A003987bi implements the bitwise-XOR, A003987 and code for A000203 can be found under that entry. - Antti Karttunen, Nov 25 2017

(PARI) a(n) = bitxor(n, sigma(n)); \\ Michel Marcus, Nov 25 2017