Numbers k such that sigma(k) > 2*k and A003415(sigma(k)) < k, where A003415 is the arithmetic derivative, and sigma is the sum of divisors function.
A347889
Numbers k such that sigma(k) > 2*k and A003415(sigma(k)) < k, where A003415 is the arithmetic derivative, and sigma is the sum of divisors function.
Terms
- a(0) =18a(1) =36a(2) =100a(3) =144a(4) =324a(5) =400a(6) =576a(7) =784a(8) =900a(9) =1296a(10) =1458a(11) =1600a(12) =1936a(13) =2304a(14) =2500a(15) =2704a(16) =2916a(17) =3136a(18) =3600a(19) =4624a(20) =5184a(21) =5202a(22) =5776a(23) =6400a(24) =7744a(25) =8464a(26) =9216a(27) =9604a(28) =10000a(29) =10404
External references
- oeis: A347889