Numbers k such that the sum of divisors of k (A000203) and the sum of proper divisors of k (A001065) are both triangular numbers (A000217).

A329704

Numbers k such that the sum of divisors of k (A000203) and the sum of proper divisors of k (A001065) are both triangular numbers (A000217).

Terms

    a(0) =1a(1) =2a(2) =5a(3) =36a(4) =54a(5) =441a(6) =473a(7) =6525a(8) =52577a(9) =124025a(10) =683820a(11) =1513754a(12) =1920552a(13) =6079931a(14) =6762923a(15) =14751657a(16) =17052782a(17) =17310942a(18) =36543714a(19) =49919939a(20) =60260967a(21) =251849052a(22) =364535720a(23) =372476909a(24) =562047389a(25) =670395564a(26) =670440852a(27) =783856979a(28) =824626800a(29) =1084201689

External references