Numbers n such that phi(n)*sigma(n)=phi(n-1)*sigma(n-1) (phi is the Euler totient function A000010 and sigma is the sum-of-divisors function A000203).

A140790

Numbers n such that phi(n)*sigma(n)=phi(n-1)*sigma(n-1) (phi is the Euler totient function A000010 and sigma is the sum-of-divisors function A000203).

Terms

    a(0) =6a(1) =56a(2) =57a(3) =124a(4) =136a(5) =148a(6) =176a(7) =305a(8) =352a(9) =645a(10) =1016a(11) =2465a(12) =19305a(13) =61132a(14) =162525a(15) =476672a(16) =567645a(17) =712725a(18) =801945a(19) =2435489a(20) =3346400a(21) =3885057a(22) =4556000a(23) =8085561a(24) =8369361a(25) =12516693a(26) =22702120a(27) =29628801a(28) =83884032a(29) =83994625

External references