A033088 Numbers in which all pairs of consecutive digits differ by 2.

1, 2, 3, 4, 5, 6, 7, 8, 9, 13, 20, 24, 31, 35, 42, 46, 53, 57, 64, 68, 75, 79, 86, 97, 131, 135, 202, 242, 246, 313, 353, 357, 420, 424, 464, 468, 531, 535, 575, 579, 642, 646, 686, 753, 757, 797, 864, 868, 975, 979, 1313, 1353, 1357, 2020

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Comments

If we restrict the maximum number of digits in the number to n, n >= 1, the sequence is finite and the last term is 9797...97 if n is even or 9797..9 if n is odd. - Enrique Navarrete, Dec 01 2017

Links

• Iain Fox, Table of n, a(n) for n = 1..947

Programs

PARI

is(n) = for(i=2, #n=digits(n), if(abs(n[i]-n[i-1]) != 2, return(0))); 1 \\ Iain Fox, Dec 01 2017