Numbers k such that phi(k) + sigma(k) = (5/2)*k.

A115747

Numbers k such that phi(k) + sigma(k) = (5/2)*k.

Terms

    a(0) =18a(1) =20a(2) =88a(3) =368a(4) =1504a(5) =24448a(6) =98048a(7) =5238976a(8) =25161728a(9) =2730992944a(10) =33995232256a(11) =412316336128

External references