A366964 Numbers whose difference between the largest and smallest digits is equal to 7.

18, 29, 70, 81, 92, 107, 118, 128, 138, 148, 158, 168, 170, 178, 181, 182, 183, 184, 185, 186, 187, 188, 207, 218, 229, 239, 249, 259, 269, 270, 279, 281, 289, 292, 293, 294, 295, 296, 297, 298, 299, 307, 318, 329, 370, 381, 392, 407, 418, 429, 470, 481, 492

Offset

1,1

Comments

The number of n-digit terms is 23*8^(n-1) - 41*7^(n-1) + 2^n*3^(n+1).

Links

Table of n, a(n) for n=1..53.

Mathematica

Select[Range[500], Max[d=IntegerDigits[#]]-Min[d]==7 &]

Prog

(Python)
def ok(n): return max(d:=list(map(int, str(n))))-min(d) == 7
print([k for k in range(500) if ok(k)]) # Michael S. Branicky, Oct 30 2023
(PARI) isok(n) = my(d=digits(n)); vecmax(d) - vecmin(d) == 7; \\ Michel Marcus, Nov 05 2023

Crossrefs

Cf. A037904.

Cf. A010785 (difference = 0), A366958 (difference = 1), A366959 (difference = 2), A366960 (difference = 3), A366961 (difference = 4), A366962 (difference = 5), A366963 (difference = 6), A366965 (difference = 8), A366966 (difference = 9).

Sequence in context: A205871 A144833 A259635 * A032612 A151700 A154367

Adjacent sequences: A366961 A366962 A366963 * A366965 A366966 A366967

Keyword

nonn,base,easy

Author

Stefano Spezia, Oct 30 2023

Status

approved