a(n) is the smallest number of the form k + reverse(k) for exactly n integers k, or -1 if no such number exists.

A072041

a(n) is the smallest number of the form k + reverse(k) for exactly n integers k, or -1 if no such number exists.

Terms

    a(0) =1a(1) =0a(2) =22a(3) =33a(4) =44a(5) =55a(6) =66a(7) =77a(8) =88a(9) =99a(10) =1111a(11) =-1a(12) =2552a(13) =-1a(14) =2662a(15) =3443a(16) =2772a(17) =-1a(18) =2882a(19) =-1a(20) =2992a(21) =3663a(22) =-1a(23) =-1a(24) =3773a(25) =5445a(26) =-1a(27) =3883a(28) =4664a(29) =-1

External references