A030998 Write n in base 7 and juxtapose.

0, 1, 2, 3, 4, 5, 6, 1, 0, 1, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 2, 0, 2, 1, 2, 2, 2, 3, 2, 4, 2, 5, 2, 6, 3, 0, 3, 1, 3, 2, 3, 3, 3, 4, 3, 5, 3, 6, 4, 0, 4, 1, 4, 2, 4, 3, 4, 4, 4, 5, 4, 6, 5, 0, 5, 1, 5, 2, 5, 3, 5, 4, 5, 5, 5, 6, 6, 0, 6, 1, 6, 2, 6, 3, 6, 4, 6, 5, 6, 6

Offset: 0

Author

Clark Kimberling

Keywords

• nonn
• base
• cons
• easy
• tabf

Comments

An irregular table in which the n-th row lists the base-7 digits of n. - Jason Kimberley, Dec 07 2012

The base-7 Champernowne constant: it is normal in base 7. - Jason Kimberley, Dec 07 2012

Crossrefs

Tables in which the n-th row lists the base b digits of n: A030190 and A030302 (b=2), A003137 and A054635 (b=3), A030373 (b=4), A031219 (b=5), A030548 (b=6), this sequence (b=7), A031035 and A054634 (b=8), A031076 (b=9), A007376 and A033307 (b=10). - Jason Kimberley, Dec 06 2012

Cf. A007093.

Programs

Magma

[0]cat &cat[Reverse(IntegerToSequence(n,7)):n in[1..31]]; // Jason Kimberley, Dec 07 2012

Mathematica

Flatten[IntegerDigits[#,7]&/@Range[0,60]]  (* Harvey P. Dale, Mar 04 2011 *)
almostNatural[n_, b_] := Block[{m = 0, d = n, i = 1, l, p}, While[m <= d, l = m; m = (b - 1) i*b^(i - 1) + l; i++]; i--; p = Mod[d - l, i]; q = Floor[(d - l)/i] + b^(i - 1); If[p != 0, IntegerDigits[q, b][[p]], Mod[q - 1, b]]]; Array[ almostNatural[#, 7] &, 105, 0] (* Robert G. Wilson v, Jun 29 2014 *)

Python

from itertools import count, chain, islice
from sympy.ntheory.factor_ import digits
def A030998_gen(): return chain.from_iterable(digits(m, 7)[1:] for m in count(0))
A030998_list = list(islice(A030998_gen(), 30)) # Chai Wah Wu, Jan 07 2022