Number of numbers with at most n digits whose square is a palindrome.

Terms

a(0) =4a(1) =7a(2) =15a(3) =20a(4) =31a(5) =37a(6) =56a(7) =70a(8) =95a(9) =113a(10) =162a(11) =193a(12) =264a(13) =310a(14) =415a(15) =486a(16) =640a(17) =741a(18) =950a(19) =1082a(20) =1374a(21) =1556a(22) =1940a(23) =2176a(24) =2673a(25) =2975a(26) =3611a(27) =3994a(28) =4793a(29) =5268