A236689 The sum of two neighboring digits is a palindrome; a(n) is the smallest possible nonnegative integer not occurring earlier.

0, 1, 2, 3, 4, 5, 6, 10, 7, 11, 8, 12, 9, 20, 13, 14, 15, 16, 17, 18, 30, 21, 22, 23, 24, 25, 26, 27, 29, 200, 31, 32, 33, 34, 35, 36, 38, 100, 40, 41, 42, 43, 44, 45, 47, 101, 50, 51, 52, 53, 54, 56, 102, 60, 61, 62, 63, 65, 103, 80, 70, 71, 72, 74, 104

Offset: 0

Author

Eric Angelini and M. F. Hasler, Jan 29 2014

Keywords

• nonn
• base

Comments

The sum of two digits is a palindrome iff it is less than 10 or equal to 11. Therefore, numbers with substrings 19, 28, 37, 39, 46, ... (this is not A065207) can never occur, and this is not a permutation of the nonnegative integers.

Links

• E. Angelini, Palindromes -- with digits, SeqFan List, Jan 27 2014.

Crossrefs

Cf. A228730.

Programs

PARI

a=u=0;(isp(s)=s<10||s==11);for(n=1,100,print1(a",");u+=1<1,d[j-1],a%10)+d[j])&&next;k=(k\10^(#d-j)+1)*10^(#d-j)-1;next(2));a=k;break))