A244815 The hexagonal spiral of Champernowne, read along the 210-degree ray.

1, 6, 3, 2, 3, 4, 5, 8, 0, 1, 3, 6, 1, 4, 4, 2, 3, 3, 3, 0, 5, 4, 5, 8, 6, 8, 3, 7, 9, 9, 9, 1, 1, 1, 1, 1, 7, 1, 9, 1, 7, 1, 1, 1, 1, 1, 7, 1, 9, 2, 7, 2, 1, 2, 1, 2, 7, 2, 9, 2, 7, 3, 1, 3, 1, 3, 7, 3, 9, 3, 7, 4, 1, 4, 1, 4, 7, 4, 9, 4, 7, 5, 1, 5, 1, 5, 7, 5, 9, 6, 7, 6, 1, 6, 1, 7, 7, 7, 9, 7, 7, 7, 1, 8, 1

Offset

1,2

Links

Table of n, a(n) for n=1..105.

Formula

(3n^2 - 4n + 2)th almost natural number (A033307), Also see formula section of A056105.

Example

see A244807 example section for its diagram.

Mathematica

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]]]; f[n_] := 3n^2 - 4n + 2 (* see formula section of A244807 *); Array[ almostNatural[ f@#, 10] &, 105]

Crossrefs

Cf. A007376, A056109, A244807, A244808, A244809, A244810, A244811, A244812, A244813, A244814, A244816, A244817, A244818.

Sequence in context: A106224 A254571 A360562 * A226579 A129203 A083946

Adjacent sequences: A244812 A244813 A244814 * A244816 A244817 A244818

Keyword

nonn,easy

Author

Robert G. Wilson v, Jul 06 2014

Status

approved