Non-biquadratefree "year numbers": phi(n) = 2 phi(sigma(n)) and p^4 | n for some p>1.

A137818

Non-biquadratefree "year numbers": phi(n) = 2 phi(sigma(n)) and p^4 | n for some p>1.

Terms

    a(0) =295569a(1) =1811079a(2) =1964375a(3) =2069469a(4) =4473387a(5) =5854375a(6) =10936053a(7) =13260625a(8) =18029709a(9) =21576537a(10) =22182093a(11) =25536875a(12) =35595625a(13) =46404333a(14) =49648383a(15) =55094375a(16) =57044817a(17) =58650625a(18) =67009923a(19) =69166467a(20) =72681875a(21) =76106875

External references