A198486 Numbers with the property that all pairs of consecutive digits differ by 9.

1, 2, 3, 4, 5, 6, 7, 8, 9, 90, 909, 9090, 90909, 909090, 9090909, 90909090, 909090909, 9090909090, 90909090909, 909090909090, 9090909090909, 90909090909090, 909090909090909, 9090909090909090, 90909090909090909, 909090909090909090, 9090909090909090909

Offset

1,2

Links

Table of n, a(n) for n = 1..27

Mathematica

t = {1, 2, 3, 4, 5, 6, 7, 8, 9}; Do[AppendTo[t, 10*t[[-1]]]; AppendTo[t, 10*t[[-1]] + 9], {9}]; t (* T. D. Noe, Oct 22 2013 *)

Prog

(Python)
def A198486():
    print('Numbers whose consecutive digits differ by 9')
    for i in range(1, 100001):
        b, n = True, i
        if n > 9:
            while n > 9:
                a = abs((n // 10) % 10 - n % 10)
                if a != 9: b = False
                n = n // 10
        if b: print(i, end=', ')
    return

Crossrefs

Cf. A033075, A033088, A033081, A048406-A048410.

Sequence in context: A078188 A240511 A345406 * A061805 A280658 A061219

Adjacent sequences: A198483 A198484 A198485 * A198487 A198488 A198489

Keyword

nonn,base

Author

Pieter Stadhouders, Oct 20 2013

Extensions

More terms from T. D. Noe, Oct 22 2013

Status

approved